Category: Plastic Machining

Machining Acrylonitrile Butadiene Styrene (ABS) A Plastics Guide

June 22, 2021

An Informational Brief on Polymer Machining

 

Known for its ease of machining, coloring and adaptability to additives, ABS is a versatile performance thermoplastic.  While it may be used in household toys, it is also used for mission critical applications like electrical insulators and automotive interior and exterior parts.

 

AIP has over 37 years of experience machining complex components from thermoplastics like Acrylonitrile Butadiene Styrene (ABS).  In this insightful technical brief, we will discuss what goes into machining ABS and how it differs from other manufacturing options such as metal machining, injection molding, and 3D printing.

 

Properties of ABS

 

Machinists should keep data on the properties of the thermoplastics they use.  This aids in selecting the right material for a project.  Also, it helps determine if the material is a good candidate for the end-use.  Below are some of the key characteristics of Acrylonitrile Butadiene Styrene (ABS):

 

Key Properties

  • Impact resistance
  • Chemical resistance
  • Ideal electrical insulator with added moisture resistance
  • Good strength and stiffness
  • Platable grades
  • Excellent aesthetic qualities
  • Colorable
  • Various gloss levels (Matte to High Gloss)

 

Description

ABS is one of the most common thermoplastic polymers manufactured. It is relatively cheap compared to other performance thermoplastics, such as, PEEK or VESPEL.

 

It provides good mechanical properties, including, impact resistance, toughness and rigidity compared to other common polymers. It is also easy to modify with additives to improve any of its properties. It is often a polymer of choice where aesthetics and color are concerned, since its natural color is translucent ivory to white. Pigments and additives are often added to this resin to improve the qualities based on the project needs.

 

Two major categories could be ABS for extrusion and ABS for injection molding, then high and medium impact resistance. Generally, ABS would have useful characteristics within a temperature range from −20 to 80 °C (−4 to 176 °F). As an amorphous polymer, it does not have a true melting point.

 

The table below displays an overview of the material properties, units and values for machining ABS:

 

Material Property Units Value
Tensile Elongation at Break @73 F % 20
Flexural Modulus of Elasticity @ 73 F psi 340000
Tensile Modulus of Elasticity @ 73 F psi 346000
Flexural Strength @ 73 F psi 9300
Specific Gravity @73 F ASTM D792 1.04
Tensile Strength @73 F, (ult)/(yld) psi 5500 (ult)
Notched Izod Impact @73 F ft-lb/in of notch 7.0
Heat Deflection Temperature @ 264 psi F 220
Flammability Rating UL94 HB(6.10mm)
Coefficient of Linear Thermal Expansion @73 F in/in/F 5.2E-05
Dielectric Strength, Short Term Volts/mil 450
Water Absorption, Immersion, 24 hours
Water Absorption, Saturation		 % by weight
% by weight		 0.30
0.70

 

Applications of ABS

 

ABS is mostly found in a wide variety of consumer products. Some of which include – Legos®, recorders and other musical instruments, golf club heads, household vacuums, and so on. ABS is a household staple for many consumer goods.

 

It also finds several end-use applications in the industrial sector. Applications include – automotive trim and components, inhalers, tendon prostheses, drug-delivery system tracheal tubes, enclosures for electrical and electronic assemblies, protective headgear and more.

 

Common Applications

  • Structural components
  • Automotive interior and exterior parts
  • Medical devices
  • Electrical components and assemblies
  • Toys
  • Housings/covers
  • Kitchen appliances

 

AIP Machining Capabilities: Unrivaled Expertise

 

Our close ties with the industry’s leading plastics manufacturers give us even further insight and access to technical help in material selection, sizing and manufacturing procedures. If you are looking for a trademarked material for your project, we have a host of material bases available for expert machining. Whatever your application, our machinists can help you in material selection, sizing and manufacturing techniques from concept to completion.

 

Our Suppliers

 

Machining ABS

 

Annealing ABS

As with any CNC machined part, annealing and stress-relieving is crucial to the machining process. Coolants, lubricants and trained procedures prevent cracking and crazing in a precision machined component. We recommend slow heating and cooling during the annealing process of thermoplastics. This reduces the chances of these stresses occurring from the heat generating during machining polymers like ABS. Our AIP machinists use computer controlled annealing ovens for the highest quality precision temperatures and time control. .

 

Machining ABS

PVC can be injection molded, extruded or thermoformed.  At AIP, we CNC machine compounded PVC.  For the best results, use sharp tools, avoid excessive clamping and cutting forces and use coolants to prevent overheating.  We recommend non-aromatic, water-soluble coolants because they are most suitable for ideal surface finishes and close tolerances. These include pressurized air and spray mists. Coolants also preserve and extend the life of tools.  These guidelines are general and are not a substitute for a conversation with your machinist.  For further information, speak to a CNC machinist at AIP to get specific machining information on PVC and other performance thermoplastics.

 

Although it is often blow molded, ABS can be CNC machined and milled for precision parts. ABS is manufactured in a variety of grades, but for precision machining of ABS structural parts, it is recommended to use Machine Grade ABS. For the best results, use sharp tools, avoid excessive clamping and cutting forces and use coolants to prevent overheating. We recommend non-aromatic, water-soluble coolants because they are most suitable for ideal surface finishes and close tolerances. These include pressurized air and spray mists. Coolants have the additional benefit of extending tool life as well.

 

Some companies machine both metals and plastics, which has detrimental outcomes for machined polymer products. Many past experiences have shown parts going to customer without cracks, only to develop surface cracks and warping over time due to exposure to metal machine shop fluids. Be sure to use a facility like AIP that only machines polymers.

 

Preventing Contamination

Contamination is a serious concern when machining polymer components for technically demanding industries such as aerospace and medical sciences. To ensure the highest level of sanitation down to the sub-molecular level, AIP Precision Machining designs, heat-treats, and machines only plastics with any sub-manufactured metalwork processed outside our facility. This allows us to de-risk the process from metallic cross contamination.

 

ABS Machining Guide: Supportive Information

 

Quality Assurance Certifications
Miscellaneous Materials

 

How will the heat from your machining project affect your project? Make sure to talk to your machinist about the CLTE of your machined part.

 

Read Our Blog
 

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Understanding Heat Deflection Temperature (HDT) of Plastics

June 8, 2021

What is HDT?

 

The Heat Deflection Temperature (HDT), or Heat Distortion Temperature, is a measure of a polymer’s resistance to alteration under a given load at an elevated temperature.  It is also known as the ‘deflection temperature under load’ (DTUL) or ‘heat deflection temperature under load (HDTUL)’.  Basically, it tests the stiffness of a material as the temperature increases.

 

It is the temperature at which a polymer test bar will be bent at 0.25 mm under a given weight.  It is one of the two basic test methods for assigning a value to the performance of a plastic at high temperature.  The 0.25mm value is arbitrary and does not have any significant meaning.

 

Why is HDT significant?

 

As with any machined part, during the design phase, it is critical for a machinist to know how a material will react to heat produced while machining occurs.  Tools produce heat when they come in contact with materials and plastics have a tendency to move with heat.  In order to get a finished product with the right dimensions and tolerances, it is important to understand the heat deflection temperature of a given polymer.

 

Other reasons include:

  • HDT represents a value which can be used to compare different materials with each other
  • It is applied in product design, engineering and manufacture of products using thermoplastic components
  • A higher HDT temperature means a faster molding process in injection molding processes

 

Tests to Measure Heat Deflection Temperatures of Plastics

 

The American Society for Testing and Materials, or ASTM, standard for measuring HDT is called ASTM D 648; this standard is equivalent to the ISO 75.

 

The two common loads used in heat deflection testing are:

  • 46 MPa (67 psi) – this load is usually for softer grades of plastic like polyethylene (PE) or LDPE.
  • 8 MPa (264 psi) – this load is used for more durable grades of plastic like PEEK or polycarbonate (PC).

 

There are tests performed at higher loads such as 5.0 MPa (725 psi) or 8.0 MPa (1160 psi), but we won’t discuss them in this brief.

 

Limitations that are associated with the determination of the HDT is that the sample is not thermally isotropic and, in thick samples in particular, will contain a temperature gradient.

 

During the ASTM D 648 test, a testing rod made of the selected polymer is placed on an apparatus like the one in the diagram below.

 

 

 

Source: SEKISUI Polymer Innovation
 

The bar is molded a specific thickness and width.  The sample is then submerged in oil while the temperature incrementally increases (usually about 2 oC per minute).  The constant applied force, or load, is pressed to the midpoint of the test bar.  The temperature at which a bar of material is deformed 0.25mm is recorded as the HDT.

 

HDT at 1.8 Mpa (264 psi) Values for Common Polymers

 

 

Polymer Name Min Value (o C) Max Value (o C)
ABS – Acrylonitrile butadiene styrene 88 100
PA – Nylon Polyamide, 66 30% Glass Fiber 230 255
PAI – Polyamide-Imides (TORLON) 275 280
PBI – Polybenzimidazole (CELAZOLE) – 426.6
PC – Polycarbonate, high heat 140 180
PE – Polyethylene, 30% glass fiber 121 121
PEEK – Polyetheretherketone 150 160
PEI – Polyetherimide (ULTEM) 190 200
PP – Polypropylene (30-40% Glass fiber-reinforced) 125 140
PP – Polypropylene Homopolymer/Copolymer 50 60
PS – Polystyrene, high heat 85 100
PSU – Polysulfone 160 174
PTFE – Polytetrafluorethylene 45 50
PVC – Polyvinyl chloride, rigid 54 75
PVDF – Polyvinylidene fluoride (KYNAR) 50 125

 

Factors That Influence HDT

 

The HDT gives a short-term performance under load at elevated temperatures for a polymer by measuring the effect of temperature on stiffness.  Yet, this is only an estimate and should not be used to predict how the final part or component will perform.

 

Other factors will significantly influence the final thermal performance of an application.

 

These factors include:

  • The time of exposure to elevated temperature
  • The rate of temperature increase
  • The part geometry

 

The HDT measure for a specific polymer grade also depends on the base resin and the presence of reinforcing agents, fillers or plasticizers.

 

For instance, in the chart above, the homopolymer or copolymer of polypropylene has a HDT value range of 50-60 oC. Compare that value to the 30-40% glass-fiber reinforced grade of polypropylene, which is more than double the temperature (125-140 oC).  A factor like this would influence the material choice for a designer wanting to use polypropylene for the end use product.

 

A combination of additives will always have a different effect on the HDT and the performance of a polymer overall.

 

  • Reinforced and filled grades have a higher HDT (harder and stiffer under the heat)
  • Plasticizers decrease HDT by making the polymer softer and more flexible

 

AIP:  Unmatched Precision.  Unrivaled Experience

 

Data charts can give you the heat deflection temperature, glass transition and other values.  However, a chart can give a general idea of these values, but an entire data set with the curve of a material is the best way to determine the right material for your project.

 

Be sure to work with a plastics machining company that can provide you a wide range of data on the HDT and other values of polymers and composites.  Your machinist will be able to give you a detailed response on how the heat deflection temperature will affect your project’s design and functionality.  Talk to one our engineers at AIP about your project design, and we will work with you to provide unrivaled expertise from your project’s initial concept to completion.

 

Supporting Materials

Certifications and Technical Data Resources

 

Learn more about the material properties we consider when
working on a precision plastics machining project.

 

Read our blog on the CUT of Polymers
 

Follow AIP Precision Machining on Linkedin

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MACHINING PVC: A PLASTICS GUIDE

May 18, 2021

An Informational Brief on Polymer Machining

 

PVC, or polyvinyl chloride, is a rigid material that exhibits high corrosion resistance, high chemical resistance, low moisture absorption and excellent dielectric strength.  These qualities make it a choice material for a wide range of industries, including:  medical devices, industrial/construction components and everyday household items.  It is the world’s third largest thermoplastic material by volume only after polyethylene and polypropylene.

 

AIP has over 37 years of experience machining complex components from thermoplastics like PVC.  In this insightful technical brief, we will discuss what goes into machining PVC and how it differs from other manufacturing options such as metal machining, injection molding, and 3D printing.

 

Properties of PVC

 

All machine shops should keep data on the properties of the thermoplastics and materials they use.  The data helps in selecting the right material for a project and a material’s suitability for the end-use product.  Below are some of the key characteristics of PVC:

 

Key Properties

  • Good insultation
  • Dielectric strength
  • Durable
  • Flame Retardant
  • Low maintenance and long life span
  • Abrasion resistant
  • Light-weight
  • Chemical resistance

 

Description

Polyvinyl Chloride (PVC or vinyl) is a highly durable thermoplastic material.  It is versatile and economical for applications in medical, construction, industrial and consumer end use markets.

 

PVC has excellent dielectric strength which makes it a good insultation material.  It is also resistant to weathering, chemical rotting, corrosion, shock and abrasion – therefore, a preferred material choice for long-life and outdoor products.  PVC is resistant to all inorganic chemicals. It has very good resistance against diluted acids, diluted alkalis and aliphatic hydrocarbons. Attacked by ketones; some grades swollen or attacked by chlorinated and aromatic hydrocarbons, esters, some aromatic ethers and amines, and nitro- compounds.

 

It is available in two forms – rigid and flexible – but it is often mixed with additives to enhance properties and improve machineability.

 

The table below displays an overview of the material properties, units and values for machining PVC Gray Type 1:

 

Material Property Units Value
Tensile Elongation at Break @73 F % –
Flexural Modulus of Elasticity @ 73 F psi 455000
Tensile Modulus of Elasticity @ 73 F psi 392000
Flexural Strength @ 73 F psi –
Specific Gravity @73 F ASTM D792 1.43
Tensile Strength @73 F, (ult)/(yld) psi 7300 (yld)
Notched Izod Impact @73 F ft-lb/in of notch 0.7
Heat Deflection Temperature @ 264 psi F 169
Flammability Rating UL94 –
Coefficient of Linear Thermal Expansion @73 F in/in/F E-831(TMA)
Dielectric Strength, Short Term Volts/mil –
Water Absorption, Immersion, 24
Water Absorption, Saturation		 % by weight
% by weight		 –
–

 

Applications of PVC

 

PVC comes in two general forms – rigid and flexible.  However, it can be combined with several different materials to enhance its qualities for use in a range of applications from medical devices to industrial construction components.  Here is a list of the most common applications:

 

Common Applications

 

Application Rigid PVC Flexible PVC
Construction Window Frames, Pipes, House Siding, Ports, Roofing Waterproof Membranes, Cable Insultations, Roof Lining, Greenhouses
Domestic Curtain Rails, Drawer Sides, aminates, Audio and Videotape Cases, Records Flooring, Wall Coverings, Shower Curtains, Leather Cloth, Hosepipes
Packaging Bottles, Blister Packs, Transparent Packs and Punnets Cling Film
Transport Car Seat Backs Under Seal, Roof Linings, Leather Cloth Upholstery, Wiring Insultation, Window Seals, Decorative Trim
Medical – Oxygen Tents, Bags and Tubing For Blood Transfusions, Drips and Dialysis Liquids
Clothing Safety Equipment Waterproofs for Fishermen and Emergency Services, Life-Jackets, Shoes, Aprons and Baby Pants
Electrical Insultation pipes, jacketing, electricity distribution boxes, switches, transparent distributor box housings, plug housings and battery terminals Cable and wire insultation, plugs, cable jackets, sockets, sable heads and distributors
Other Credit Cards, Traffic Signage Conveyor Belts, Inflatables, sports goods, toys, garden hoses

 

AIP Machining Capabilities: Unrivaled Expertise

 

Our close ties with the industry’s leading plastics manufacturers give us even further insight and access to technical help in material selection, sizing and manufacturing procedures.  If you are looking for a trademarked material for your project, we have a host of material bases available for expert machining.  Whatever your application, our machinists can help you in material selection, sizing and manufacturing techniques from concept to completion.

 

Machining PVC

 

Annealing PVC

Annealing and stress-relieving prevents cracking and crazing in a precision machined component with lubricants, cooling agents and trained procedures.  We recommend slow heating and cooling during the annealing process of thermoplastics.  This reduces the chances of these stresses occurring from the heat generating during machining polymers like PVC.  Our AIP machinists use computer controlled annealing ovens for the highest quality precision temperatures and time control.  If you have a specific question about the annealing process for PVC or other thermoplastics, our machinists at AIP can provide an in-depth consultation.

 

Machining PVC

PVC can be injection molded, extruded or thermoformed.  At AIP, we CNC machine compounded PVC.  For the best results, use sharp tools, avoid excessive clamping and cutting forces and use coolants to prevent overheating.  We recommend non-aromatic, water-soluble coolants because they are most suitable for ideal surface finishes and close tolerances. These include pressurized air and spray mists. Coolants also preserve and extend the life of tools.  These guidelines are general and are not a substitute for a conversation with your machinist.  For further information, speak to a CNC machinist at AIP to get specific machining information on PVC and other performance thermoplastics.

 

Some companies machine both metals and plastics, which has detrimental outcomes for machined polymer products.  Past experiences have shown parts going to customer without cracks, only to develop surface cracks and warping over time due to exposure to metal machine shop fluids. Be sure to use a facility like AIP that only machines polymers.

 

Preventing Contamination

Contamination is a serious concern when machining polymer components for technically demanding industries such as aerospace and medical sciences. To ensure the highest level of sanitation down to the sub-molecular level, AIP Precision Machining designs, heat-treats, and machines only plastics with any sub-manufactured metalwork processed outside our facility.  This allows us to de-risk the process from metallic cross contamination.

 

PVC Machining Guide: Supportive Information

 

Quality Assurance Certifications
Miscellaneous Materials

 

Looking for more plastics machining guides on polymers with chemical resistance?

 

Read Our PCTFE Machining Guide
 

 

Follow AIP Precision Machining on Linkedin

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How Continuous Use Temperature Relates to the Stability of a Machined Polymer

April 27, 2021

The continuous service temperature, or continuous use temperature (CUT), is the maximum ambient service temperature in air that a material can withstand and maintain 50% of its initial physical properties after long-term service.

 

What is long-term service?  It’s defined as 100,000 hours of service – well over 11 years, if used 24 hours a day, 365 days a year.  The continuous use temperature property tells machinists and users what will happen to a part over the course of roughly 11 years of continuous use.  It’s the temperature at which the polymer will degrade, embrittle and start to break down.

 

It is important for the designers, engineers and users to take this measurement into consideration for CNC machining.  During the design phase, this not only helps with initial material selection, but plays a role in predicting the life span of a part.  At AIP, we take great care in providing unrivaled results to ensure the optimal dimensions and properties for machined polymers and composites.  Join us in this technical brief as we give an in-depth explanation of the continuous use temperature for machined polymers.

 

What Affects Continuous Use Temperature?

 

The base material polymer structure affects the continuous use temperature of a machined part.  The time that is involved and the loading levels that are used in the testing can affect the CUT value.  Also, additives and reinforcements should be taken into consideration.  They may have an effect on the maximum continuous use temperature value.

 

Tests to Measure Continuous Use Temperature of Plastics

 

The continuous use temperature is measured in degrees Celsius (o C) or Fahrenheit (o F).  One of the common tests used to compare different materials in terms of continuous use temperature is the Underwriter Laboratory (UL) Relative Thermal Index or RTI.

 

UL 746B

This test method is used to determine RTI values.  The RTI is based on a loss of properties of the plastic versus time. In general, when the plastic is exposed to this maximum continuous use temperature – good, long-term performance is observed. However, it does not consider short-term thermal spikes.

 

RTI gives an indication of the aging temperature that a material can endure for 100,000 hours and still retain at least half of the initial property being measured. However, different properties for materials decay at dissimilar rates. This is the primary reason why often RTI values are associated with a particular property and the related CUTs are given as a range of values rather than as a single value.

 

Determination of RTI Value

  1. Groups of test pieces are placed in ovens at four different pre-set temperatures.
  2. At specified time intervals, the test pieces are taken out of the ovens and tested for mechanical and electrical properties of interest.
  3. The results are plotted on a property versus time graph until the property that is being tested declines to 50 percent or less of its initial value.

 

In this analysis, the 50 percent value of the property is referred to as the half-life of that particular property. The half-life values are then, plotted against the reciprocal of the absolute aging temperature. This plot results in a straight line that can be extrapolated, if needed, to indicate the half-life of the property at other temperatures.

 

The results that are obtained in this testing procedure can also be compared to a material with a known aging performance.

 

Types of RTI

There are three general classes of properties that are associated with the RTI.  The three values for a particular polymer are often different from each other.  They are the following:

  • The RTI Electrical that is associated with insulating properties.
  • The RTI Mechanical Impact which is related to the impact resistance, toughness, elongation and flexibility.
  • And, the RTI Mechanical Strength that is associated with the mechanical properties or the structural integrity of the plastics.

 

Continuous Use Temperature Values for Common Polymers

 

Polymer Name Min Value (o C) Max Value (o C)
ABS – Acrylonitrile butadiene styrene -20 80
PA – Nylon Polyamide, 66 30% Glass Fiber 100 150
PAI – Polyamide-Imides (TORLON) -196 220-280
PBI – Polybenzimidazole (CELAZOLE) 204 540
PC – Polycarbonate, high heat 100 140
PE – Polyethylene, 30% glass fiber 100 130
PEEK – Polyetheretherketone 154 260
PEI – Polyetherimide (ULTEM) 170 170
PP – Polypropylene 100 130
PS – Polystyrene, high heat 75 90
PSU – Polysulfone 150 180
PTFE – Polytetrafluorethylene – 260
PVC – Polyvinyl chloride, rigid 50 80
PVDF – Polyvinylidene fluoride (KYNAR) – 149

 

Continuous use Temperature Does Not Define Polymer Strength

 

It is important to note that the continuous use temperature does not define a part’s ability to handle a load under a specific temperature. One material that proves this is PTFE. PTFE is an advanced thermoplastic that can handle 500 o F continuous service without breakdown. Yet, it is a soft material, which bends easily at room temperature. This property is called the heat deflection temperature (HDT), which is another important property to consider.

 

AIP: Unrivaled Precision Machining

 

Data charts can give you the Continuous Use Temperature, glass transition and other values. However, a chart can give a general idea of these values, but an entire data set with the curve of a material is the best way to determine the right material for your project.

 

Be sure to work with a plastics machining company that can provide you a wide range of data on the CUT of polymers and composites. Your sales engineer will be able to give you a detailed response on how the continuous use temperature will affect your project’s design and functionality. Talk to one our engineers at AIP about your project design, and we will work with you to provide unrivaled expertise from your project’s initial concept to completion.

 

Supportive Information

 

Certifications and Regulatory Resources

 

Our team is dedicated to providing unparalleled, quality machined polymers and composites. Learn more about the material properties we consider when working on a project.

 

Read our blog on Moisture Absorption
 

 

Follow AIP Precision Machining on Linkedin

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How Moisture Absorption Relates to the Stability of a Machined Polymer

April 13, 2021

Most polymers have a natural tendency to absorb water. In fact, some superabsorbent polymers are highly sought after in advanced applications for medical, construction and more. Yet, moisture absorption of thermoplastics leads to changes with regard to processing and properties.

 

It is crucial for machinists and designers to understand the moisture absorption of thermoplastics for CNC machining. During the design phase, this not only helps with initial material selection, but plays a role in predicting the life span of a part. At AIP, we take great care in providing unrivaled results to ensure the optimal dimensions and properties for machined polymers and composites. Join us in this technical brief as we give an in-depth explanation of the effects of moisture absorption for machined polymers.

 

Plastics Machining and the Importance of Water Absorption

 

Moisture / water absorption is the capacity of a plastic or a polymer to absorb moisture from its environment. Absorbed moisture sometimes acts as a plasticizer, reducing the glass transition temperature and strength of plastic (this is a reversible side effect). However, absorbed water also can lead to irreversible degradation of the polymer structure.

 

Some effects include:

  • Dimensional and mass changes (swelling) caused by water absorption
  • Extraction of water-soluble components
  • Changes in mechanical (elasticity, tensile strength, impact strength) and electrical performance

 

Water absorption is expressed as increase in weight percent or % weight gain of a plastic specimen under the following testing procedures:

  • Water Absorption 24 hrs at 23°C – Immersion of a plastic specimen in distilled water during 24 hours at 23°C
  • Water Absorption 24 hrs at 100°C– Immersion of a plastic specimen in distilled boiling water during 24 hours Water Absorption at saturation – Immersion of a plastic specimen in distilled water at 23°C.  Measurement occurs when the polymer does not absorb water anymore
  • Water Absorption at Equilibrium– Plastic specimen is exposed to a humid environment — generally at 50% relative humidity — at a specified temperature — 23°C or 73.4°F — for 24 hours

 

(Source: Omnexus)

 

Exposure to humidity, immersion and boiling water can result in different material responses. The equilibrium moisture content can be used to compare the amount of water absorbed by different types of plastics when they are exposed to moisture.

 

Plastics Processing and Properties

 

Polymers are affected by moisture from their environment or from simply sitting on a shelf waiting to be used.  This is not a huge concern, but when the moisture absorption reaches more than 1% or 2%+, this can result in enough dimensional movement to create concerns.

 

Moisture Absorption Affects:

  • Mechanical properties
  • Wear properties
  • Dimensions

 

For example, parts made from TORLON (PAI) require special attention due to a 1.7% moisture at saturation value.  While this number may not sound like much, it is enough to cause a precision machined TORLON part to exceed tolerance; in this scenario, the part cannot be used.

 

Therefore, it is important to properly package these mission critical polymers for lasting shelf-life and function.  This can be achieved in two ways:  1) Vacuum-sealing them in a moisture-impermeable layer or 2) packaging them with bags of desiccant.  This prevents moisture uptake in humid environments.

 

Tests to Measure Water Absorption of Plastics

 

Source

 

ASTM D570 – Standard Test Method for Water Absorption of Plastics

 

This test method for rate of water absorption has two main functions:

  1. A guide to the proportion of water absorbed by a material and consequently, in those cases where the relationships between moisture and electrical or mechanical properties, dimensions, or appearance have been determined, as a guide to the effects of exposure to water or humid conditions on such properties.
  2. A control test on the uniformity of a product. It is particularly applicable to sheet, rod, and tube arms when the test is made on the finished product.

 

Procedure:  Parts are dried in an oven for a specified time and temperature and then placed in a desiccator to cool.  Upon cooling, the specimens are weighed to establish a point of reference.  The material is then submerged in water at standardized conditions (usually 23°C for 24 hours or until equilibrium).  Specimens are removed from the liquid, dried and weighed.

 

What affects water absorption?

  • Type of plastic
  • Morphology (crystalline, amorphous…)
  • Type and proportion of additives, fillers and reinforcements used
  • Fiber fraction and orientation (in composites)
  • Relative humidity and temperature
  • Length of exposure

 

Water Absorption Values for Common Polymers

 

Polymer Name Min Value (% weight) Max Value (% weight)
ABS – Acrylonitrile butadiene styrene 0.05 1.80
PA – Nylon Polyamide, 66 30% Glass Fiber 0.80 1.10
PAI – Polyamide-Imides (TORLON) 0.10 0.30
PBI – Polybenzimidazole (CELAZOLE) 0.4 5
PC – Polycarbonate, high heat 0.10 0.20
PE – Polyethylene, 30% glass fiber 0.02 0.06
PEEK – Polyetheretherketone 0.10 0.50
PEI – Polyetherimide (ULTEM) 0.20 0.30
PP – Polypropylene 0.01 0.10
PS – Polystyrene, high heat 0.01 0.07
PSU – Polysulfone 0.20 0.80
PTFE – Polytetrafluorethylene 0.005 0.015
PVC – Polyvinyl chloride, rigid 0.04 0.40
PVDF – Polyvinylidene fluoride (KYNAR) 0.03 0.05

 

As the chart notes, some polymers such as Nylon (PA) have a higher rate of % gain from moisture absorption.  However, polymers like PVDF and PTFE have a very low % gain in weight after the ASTM D570 test – which makes them excellent candidates for applications where moisture is a factor.

 

Performance thermoplastics are often exposed to high temperature applications (aircraft engines) which also absorb high levels of moisture.  This is common in materials such as PBI (Celazole) and PAI (Torlon), since these polymers absorb moisture at high rates but are also specified in high temperature applications.

 

Basically, what can happen is that these materials absorb the moisture if not properly stored and packaged.  Then if subject to high levels of heat without time for the moisture to dissipate, the internal moisture boils and turns to steam causing the parts to crack and blister.

 

Managing Moisture Absorption

For predictable machined part fit and performance, stock shapes and finished parts should be stored in a dry environment.  Both finished parts and stock shapes should be packed in moisture barrier packaging.  Only open packaging just prior to use.  In the event that a part may have adsorbed so much moisture as to risk shocking it when placing it in high temperature or vacuum service, consider drying the material prior to use or re-use.

 

Your machining facility will have specifications on temperature and storage procedures for all polymers, stock shapes and components.  When it comes to critical applications, work with a machine shop that has high standards for storing products.  After all, machining a polymer is only part of the entire process; wasted machining, revenue and parts is not worth risking poor storage conditions.  The table below shows some common packaging for polymers to increase and preserve shelf-life.

 

 

Generally, you can find a polymer’s 24 Hour and Saturation Moisture Absorption Values on a data chart.  A chart can give a general idea of the moisture absorption, but an entire data set with the curve of a material is the best way to determine the right material for your project.  Be sure to work with a plastics machining company that can provide you a wide range of data on the moisture absorption of polymers and composites.  Your machinist will be able to identify how moisture and humidity will affect your project’s design and functionality.  Talk to one our engineers at AIP about your project design, and we will work with you to provide unrivaled expertise from your project’s initial concept to completion.

 

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Putting the final touches on your CNC Machined Part: Finishing, Deburring, Painting and Polishing

March 9, 2021

The last step in finishing a part is to apply an appropriate finish. Finishing a machined part can be as simple as smoothing off the burrs and other sharp edges or painting and coating the material to improve aesthetics and functionality. In the initial design phase of your project, talk to your machinist about the finishing processes to get a highly precise and extremely resilient piece.

 

AIP has over 37 years of experience machining complex components from thermoplastics. In this technical blog, we discuss putting the finishing touches on your CNC machined part, including: finishing, deburring, painting and polishing.

 

Common Finishing Techniques for CNC Machining

 

As Machined

The “as machined” part is the standard finish for the material. Many times, it has visible tools marks, but it has no additional cost to the machining process. Also, this finish has the tightest dimensional tolerances. Our standard AIP machined finish has almost no tool marks – we go the extra mile for our customers to produce unparalleled results. Taking pride in our craftsmanship and attention to detail is what makes us stand out from other CNC machine shops in the industry.

 

Deburring

Deburring involves the removal of burrs and sharp edges. A variety of tools may be used including die grinders, deburring scrapers, files and various stones.

 

Painting

Painting a finished part fulfills two requirements: 1) improves appearance (aesthetics) and 2) enhances the function of the piece.

 

Various coatings and treatments provide protection and add color to the surface of machined parts:

 

  • Plating: Chrome plating, nickel plating and other kinds of metal can be applied via plating processes.
  • Painting: Resins generally come in many different colors and can be painted to fit the exact specifications of a project.
  • Powder Coating: Powder coating adds a wear and corrosion finish to the surface of a part. It has a higher impact resistance compared to anodizing and a large range of colors are available.
  • Silk Screening: This is an inexpensive way to print text or logos on the surface of a CNC machined part. The print can be applied only to external surfaces on a part.

 

Polishing

There are several different types of polishing to finish off a machined plastic part. Here are a few of the most common methods:

 

  • Vibratory Polishing: This method uses rotating or vibrating tumblers along with a variety of media to deburr, remove tooling marks and polish parts. It is convenient for large bulk items that need polishing. Put them in a tumbler and go do something else.
  • Bead Blasting: This process uses compressed air to blast an abrasive media at the material. This method is done inside of a blast cabinet. It adds a uniform matte or satin surface finish on a machined part and removes all tool marks.
  • Filing: Filing down the edges or burrs on a small machined part is a craft, however, a good file offers efficiency. This technique is often taught to apprentice machinists.
  • Stoning: Machinists use stones and oil to deburr and knock off sharp edges that tear and snag.

 

Case Study: Making a Splash with Machined PPS

 

The finishing plays a major role in the quality, durability and utility of a machined plastic part. For our client in the theme park business, it meant reducing a water ride’s overhauls by 25 times.

 

When a popular ride experiences downtime, the negative impact on guest satisfaction is immediate. Lost interest and value in a park experience can mean loss of customers and in effect revenue. For our Florida theme park client, this was the case with their log flume coaster ride. While this ride was thrilling for its daily customers, the ride required nightly repair and part replacement. They specifically needed new wheel bushings from a more innovative material.

 

Since we had worked with this client previously, we were able to assess the project. The log flume’s passenger carts originally used bronze bushings due to their nice, soft wear, however, the speed and load of the carts generated a great deal of heat when the ride would plunge into its steep vertical drop. The moment each cart hit the cool water below, the wheel bushings would suddenly experience “shock cooling” damage.

 

Between this and the constant exposure to chemicals in the water (chlorine), the bronze bushings had a very short life cycle.

 

Our team selected Quadrant’s BG1326, a bearing-grade high-performance thermoplastic PPS.

 

PPS CNC Machining ExamplePPS has a low moisture absorption rate and can be machined to the exact tolerances necessary for clearing and shaft. With low-wear, high temperature stability and a low coefficient of friction, the chosen PPS grade proved to be an excellent fit for the log flume’s wheel bushings.

 

Our machinists at AIP worked diligently with the ride engineers to ensure the PPS bushings were built to exact specifications. The chosen method for machining the parts was precision machining. This way the components could meet the precise tolerances and finishes demanded by the speed and load of the log flume.

 

The Benefits

 

The main benefit of the machined PPS bushings was the reduction in ride downtime. The previous bronze bushings required around 25 times the overhauls of the new PPS bushings. The change in materials not only saved on maintenance and inventory costs, but improved guest satisfaction with the increase in uptime.

 

The PPS bushings also removed the potential for grease to affect seals or chemicals in the water. As a self-lubricating plastic, PPS removed the need for nightly greasing the wheel bushings. The lower energy cost of the PPS material also made for a more environmentally friendly and efficient design.

 

Preventing Contamination

 

Some companies machine both metals and plastics, which can open the door to contamination of a product. Although some sources state that most CNC machining tools can be used for both metal machining and plastic machining, this is not recommended. Past experiences have shown parts going to customer without cracks, only to develop surface warpage and cracks over time due to exposure to metal machine shop fluids.

 

Mitigate contamination by working with a facility like AIP that works solely with polymers. We ensure the highest level of sanitation down to the sub-molecular level by designing, heat-treating and machining only plastics. This allows us to eliminate the risk of metallic cross contamination.

 

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How to Select the Right Material for Your CNC Machined Part

December 22, 2020

3 Tips from the Plastics Machining Pros on choosing the most suitable material for your machined polymer components

 

CNC machining produces high-end, mission critical products for many markets and industries. It allows for tight tolerances on part dimensions and complex designs. However, before the machining can happen, the design must be completely planned out with your manufacturer. In order to get the best outcome for the design, you must choose the right polymer for your precision machined project.

 

As a precision plastics machining company, we work closely with our clients on the initial design conception for their project. Specialized in understanding and envisioning how to manufacture extremely complex designs, our team can see beyond the concept through to the exact specifications and output of the finished product. We prioritize all aspects of the material selection in order to deliver the optimal machined product to fulfill your design.

 

In our latest blog series on Design for Manufacture (DFM), we discuss 3 tips for material selection to discuss with your machinist and precision polymer manufacturer.

 

Finding the Right Material

 

Material selection for your design is a critical step in the design process. Not only do you need to select a material that is suitable for your product, but also discuss with your manufacturer cost effective options. Here are some basic details to cover with your manufacturer to get the optimal material for your project:

 

#1 Define material requirements:

What is the purpose or end use of the component? This includes environment considerations – such as whether or not the material will undergo extreme temperature, pressure, chemicals or wear.

 

Some material properties to consider include the following:

 

  • Electrical properties – Does the material need to act as a dielectric (act as an insulator rather than a conductor)?
  • Mechanical properties – How strong does the material need to be?
  • Chemical Resistant – Will the material be exposed to chemicals often?
  • Wear / Friction – How durable should the material be?
  • Color – What color does the part need to be?
  • Optical properties – Does the material need to be reflective or transparent?
  • Thermal properties – How heat resistant does it need to be?
  • Flammability – How flame/burn resistant does the material need to be?
  • Standards – Does the part need to follow industry standards and regulations? Check that your machining facility has all of the proper registrations.

 

#2 Identify candidate materials:

Consider all of your options for machined polymers. Some are more suitable for the medical environment versus those that would be chosen for aviation and defense applications.

 

Speak to your machinist and manufacturer about the material options available for your project. They will have a portfolio of materials that they can assess to find the optimal and cost-effective solution for you. Additionally, be sure your manufacturer has vast experience machining the materials you are considering.

 

#3 Select the most suitable material:

You will most likely need to pinpoint the most important features of your design that you cannot compromise on (for example, mechanical performance and cost). The manufacturability and overall cost of your project will influence your material choice. For instance, the more material your part uses, the more expensive it will be. Also, specialty materials such as PEEK and VESPEL will cost more.

 

Case Study: Choosing a Life-Saving Material To Reduce Brain Surgeries

 

Choosing the right material is not only essential in the design phase, but it can be life-saving. In our experience working with the medical industry, we know our clients prioritize biocompatibility, durability and mechanical stability in machined parts for medical devices.

 

In our recent case study, we worked with Neurosurgeon Rohit Khanna to develop a device to help lower the need for additional surgeries in patients of traumatic brain injuries or strokes. The device, known as a dynamic telescopic craniotomy, holds a portion of the skull (or bone flap) and the rest of the skull together, while enabling the brain to swell and expand. The device would significantly lower the need for repeat surgeries in patients, thus lowering the chances of morbidity.

 

PEEK Product for brain surgeriesOur team of designers, engineers and machinists worked closely with Dr. Khanna to develop a prototype for the project. The parameters for the material were steep: implantable, moisture resistance, biocompatibility, sterilizable and mechanical stability under pressure. We determined that medical grade PEEK was the ideal candidate to build the prototype, since it was renowned for its ductility, long-term implantation and biocompatibility. In collaboration with Dr. Khanna, we designed a plate-like thermoplastic PEEK device that holds the bone flap together and flexes in different directions if and when the brain swells.

 

Learn more about our work with Dr. Khanna and medical grade PEEK here.

 

AIP Precision: Polymer and Composite Material Expertise

 

Man Quality Assurance testing Peek Product

 

We are proud to offer a quality assurance process that focuses on actual product quality, fast delivery and cost-effective options. Our team of machinists provide the highest level of engineering expertise from initial design conception to a finished machined component. Our facility strictly machines polymers and composites, so you know that your product will be free of contamination and impurities. Additionally, we are not bound to any one source of raw materials which provides our customers an unbiased material selection process.

 

Our skilled team has over 37 years of working with professionals and OEMs in the following industries: medical sciences, aerospace and defense, energy and specialized industrial sector. From sensitive environments to complex shapes, we precision machine parts for a wide range of applications. We assess quality at every step of the machining process, and hold ourselves to high standards. Our facility is FDA Registered, ITAR Certified, ISO 13485:2016, ISO 9001:2015 and AS9100D Certified. For this reason, we have the capabilities to take on diverse and varied projects. If you have an initial design conception for a machined plastic part, contact our team and we will be happy to offer a consultation on material selection and machining services.

 

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As a precision plastics machining company for medical devices, we are FDA registered to ensure the highest quality assurance for your medical machining project.

 

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What Does It Mean To Be ISO 13485:2016 Certified?

May 26, 2020

A discussion with the plastics pros at AIP on how the ISO 13485:2016 standard improves quality assurance for medical machined plastics.

 

What sets a quality management system (QMS) above the rest for medical device manufacturing and machining? Safety, sanitation and product integrity are, without a doubt, crucial for any plastics machining company working with materials for medical use.

 

How can you ascertain the validity of a company’s QMS?

 

One way to do this is to look for whether the machining shop is ISO 13485:2016 certified. This regulation requires that a certified organization demonstrate that their QMS is effectively implemented and maintained.

 

At AIP, we not only promise a quality assurance program, we are ISO 13485:2016 certified. As a precision plastics machining company, we have worked with medical OEMs to develop parts for critical medical devices for more than 35 years. We understand the value of a transparent QMS program through the ISO 13485:2016 certification.

 

If you are curious to know more about this certification, read on as we discuss more on the benefits of the ISO 13485:2016 certification.

 

What is the ISO 13485:2016 Standard?

 

ISO certification logoThe ISO 13485:2016 standard specifies requirements for a quality management system where an organization or company must demonstrate its ability to provide medical devices and related services that consistently meet customer and applicable regulatory requirements, such as sanitation in the work environment to ensure product safety.

It encompasses a broad range of organizations involved in the medical device industry. These include: design and development, production, storage and distribution, installation, or servicing of a medical device and associated activities.

 

How does this certification help AIP serve the medical market?

ISO 13485:2016 reflects our strong commitment to continual improvement and gives customers confidence in our ability to bring safe and effective products to the medical market.

 

We know that product durability and cleanliness are not just desirable within the medical industry, they’re essential. The ISO 13485:2016 compliance highlights our commitment to machining medical devices with quality custom plastic components.

 

We have been successfully audited by some of the most stringent OEMs in the orthopaedic and medical device industries. Our plastics are processed with strict hygienic procedures to ensure the highest level of sanitation down to the sub-molecular level.

 

At AIP, quality assurance is a norm not only for our customers but for ourselves. The ISO 13485:2016 certification is designed to integrate with our existing quality management system. With it, we can ensure our customers the highest-level of safety and performance for their medical machined parts.

 

What about AIP Precision Machining allows us to achieve ISO 13485:2016 certification?

 
“Anyone who tells you that it is not about the people is wrong,” said MacDonald. “While leadership provided the vision and desire to seek out ISO 13485:2016 certification, our dedicated team at AIP went the distance and got us over the finish line. It is our team who will maintain and continually enhance those key processes to make us better every day at meeting the needs of our valued customers.

 

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Machining Polypropylene (PP): A Plastics Guide

May 18, 2020

An Informational Brief on Polymer Machining

 

Since it was first polymerized in 1954 by Karl Rehn and Giulio Natta, polypropylene (PP) has become one of the leading polymer choices for a wide array of applications from automotive to commercial to medical.

 

Polypropylene plays a significant role in medical applications due to its high chemical resistance, lightweight, radiolucency and repeated autoclavability. Furthermore, medical grade PP exhibits good resistance to steam sterilization and moisture resistance. Disposable syringes, instrument or implant caddies and fluid delivery systems are the most common medical application of polypropylene. Other applications include medical vials, diagnostic devices, petri dishes, intravenous bottles, specimen bottles and surgical trays.

 

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AIP has over 35 years of experience machining complex components from thermoplastics like polypropylene. In this insightful technical brief, we will discuss what goes into machining polypropylene and how it differs from other manufacturing options such as metal machining, injection molding, and 3D printing.

 

Homopolymer vs Copolymer – What’s the Difference?

 

The two main types of polypropylene available on the market are homopolymers and copolymers. Although they share many properties, there are some differences that help guide machinists and engineers in choosing the right material for their PP application. For the purposes of this blog, we will briefly review the differences between PP homopolymer and PP copolymer.

 

PP Homopolymer PP Copolymer
  • High strength to weight ratio and stiffer & stronger than copolymer
  • Good chemical resistance and weldability
  • Good processability
  • Good impact resistance
  • Good stiffness
  • Food contact acceptable
  • Suitable for corrosion resistant structures
  • Bit softer but has better impact strength; tougher and more durable than homopolymer
  • Better stress crack resistance and low temperature toughness
  • High processability
  • High impact resistance
  • High toughness
  • Not preferable for food contact applications

 

Properties of Polypropylene

 

Keeping information about the properties of a thermoplastic beforehand is always beneficial. This helps in selecting the right thermoplastic for an application. It also assists in evaluating if the end use requirement would be fulfilled or not. Here are some of the key properties of polypropylene:

 

Polypropylene is characterized by excellent chemical resistance in corrosive environments, resistance to cleaning agents and solvents and by a high heat deflection temperature.

 

It also has great dimensional stability and is fairly easy to machine. As noted above, it is available in heat-stabilized homopolymer and copolymer grades. At AIP, we machine POLYSTONE P, PROPYLUX HS and HS2, PROTEUS LSG HS PP from MCAM, TECAPRO MT and TECAFINE PP from Ensinger. Interesting to note is that both the PROPYLUX and TECAPRO heat stabilized PP grades are available in both standard and custom colors for medical sorting and sizing organization. Whatever your application, our machinists can help you in material selection, sizing and manufacturing techniques from concept to completion.

 

Melting Point of Polypropylene – The melting point of polypropylene occurs at a range.

 

Homopolymer: 160 – 165°C
Copolymer: 135 – 159°C

 

Density of Polypropylene – PP is one of the lightest polymers among all commodity plastics. This feature makes it a suitable option for lightweight\weight saving applications.

 

Homopolymer: 0.904 – 0.908 g/cm3
Random Copolymer: 0.904 – 0.908 g/cm3
Impact Copolymer: 0.898 – 0.900 g/cm3

 

Machining Polyproylene

 

Annealing Polypropylene

Due to its low annealing temperature, PP, like any polymer under heat and pressure, has a tendency to deform during machining. The annealing process at AIP greatly reduces the chances of these stresses occurring from the heat generated during machining PP and other polymers. Our machinists use computer controlled annealing ovens for the highest quality precision machining.

 

Machining Polypropylene

As a part of the polyolefin family, PP is semi-crystalline, which means that it can be machined at tight tolerances. We recommend non-aromatic, water-soluble coolants because they are most suitable for ideal surface finishes and close tolerances.

 

Bear in mind that polypropylene has variable levels of thermal expansion and will move a great deal with slight temperature changes. Some examples are pressurized air and spray mists. Coolants have the additional benefit of extending tool life as well.

 

Some companies machine both metals and plastics, which has detrimental outcomes for clients. Many past experiences have shown parts going to customer without cracks, only to develop cracks over time due to exposure to metal machine shop fluids. Be sure to use a facility like AIP that only machines polymers.

 

Preventing Contamination

Contamination is a serious concern when machining polymer components for technically demanding industries such as aerospace and medical sciences. To ensure the highest level of sanitation down to the sub-molecular level, AIP Precision Machining designs, heat-treats, and machines only plastics with any sub-manufactured metalwork processed outside our facility. This allows us to de-risk the process from metallic cross contamination.

 

Polypropylene Machining Guide: Supportive Information

 

ISO 13485:2016 Certification
ISO 9001:2015 Certification

 

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What Makes a Plastic Medical Grade?

May 5, 2020

A discussion with the plastics pros at AIP on how to choose the right plastic for your medical application

 

When it comes to selecting a polymer for a medical application, there are a myriad of factors that play into deciding which grade of polymer is the best candidate. Of course, the number one concern in medical device design is safety of human life.

 

For this reason, trends in medical device design are moving toward miniaturization and portability. Additionally, sterilization and cleanliness continue to lead design considerations globally, requiring devices to withstand a range of chemicals and sterilization techniques.

 

As a precision plastics machining company, AIP has over 35+ years of experience working with medical OEMs to develop parts for critical medical devices. In this issue of our monthly blog, we will discuss what makes a polymer medical grade and how to choose the right polymer for a medical device application.

 

What are medical grade plastics?

 

Let’s begin with what a medical grade plastic is. Medical-grade plastics refer to plastics used to make medical products, products for in vitro diagnostics and primary packaging for pharmaceuticals.

 

Most importantly, plastics used in the medical field are coming in contact with human tissue, fluids, chemicals, drugs and many more substances. There are literally thousands of medical applications from packaging to spinal implants. Based on this information, your supplier should be familiar with the types of polymers and composites you need machined. They should additionally know the best machining process for your application. That’s why design conception is crucial as the first step.

 

1. Design requirements and constraints

 

First and foremost, what is the function of the polymer for the device?

 

Your machine shop should be asking you in depth questions about your medical application. Questions to consider include:

 

  • Should the material be biocompatible?
  • Is the product for single use?
  • Will the component undergo sterilization? If so, which method?
  • Does color and aesthetics matter in the machining process?
  • Is UV resistance needed?
  • What tolerances must be met for temperature, wear, impact, etc?

 

The following material selection flow-chart displays the overall process of developing a medical grade plastic part or device:

 

Market Needs Infographic

 

2. Industry Standards

 

What industry standards and regulations control the production of the material?

 

At AIP, our plastics are processed with strict hygienic procedures to ensure the highest level of sanitation. Make sure that your machining company is compliant and/or registered with the appropriate regulatory organizations. Some common medical certifications include the following:

 

  • ISO 10993
  • ISO 13485:2016
  • FDA Registered

 

3. Biocompatibility

 

How long does the component need to be in contact with the human body or tissue?

 

There are three categories of contact duration if a component is subject to body tissue or fluid:

 

  • Short-term contact (Less than 24 hours)
  • Medium term contact (Between 1-30 days)
  • Long-term or Permanent contact (Greater than 30 days)

 

4. Sterilization/Cleanliness

 

Will the device need to be resistant to chemicals or undergo multiple sterilizations?

 

Whether it’s a feeding tube, a drug delivery device or a surgical implant, the polymer material must be able to withstand chemical degradation and multiple sterilizations.

 

The most common sterilization methods include:

 

  • Radiation (gamma/e-beam)
  • Chemical (ETO)
  • Autoclave (steam)

 

Chemicals to consider for contact with the device could be:

  • Intravenous medications
  • Blood/Fluids/human tissue
  • Hospital cleaners – bleach, isopropyl alcohol, peroxides

 

5. Polymer Characteristics

 

What mechanical properties does the polymer need to fulfill?

 

Selecting a plastic material is based on a number of traditional material requirements such as strength, stiffness or impact resistance. Engineered thermoplastics like PC, PEEK, PPSU, POM, show excellent mechanical properties at low and high temperatures. These properties are required for a variety of climate conditions, including during transportation, where the influence of temperature on drop impact may result in different outcomes for device integrity.

 

Your machinist should be able to give you details about all the plastics in their portfolio such as:

 

  • High wear resistance
  • Tensile strength
  • Temperature resistance
  • Corrosion resistance
  • Durability
  • Dimensional stability

 

6. Aesthetics

 

Does the end product need to be a certain color or have certain qualities?

 

For instance, if it is a prosthetic for a foot, the polymer needs to be machined a certain shade to match skin tone.

 

7. Other Material Selection Factors

 

Anything else?

 

Other factors to consider and discuss with your machinist include additives for increasing the performance of the polymer, manufacturing process as well as the cost. Take into account the following:

 

  • Radiopacity
  • Conductive
  • Lubrication
  • Manufacturing feasibility
  • What manufacturing processes are you using and why?
  • Technical performance
  • Can we make this product with the material, and can we make it well?
  • Economics
  • If we can make it, can we make it for a reasonable cost?

 

At AIP, we are unrivaled experts in medical grade plastic machining.
Talk to our team about how to bring your project from concept to completion.

 

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