Archive for Thermoforming

How far does your manufactured part travel to get painted?

How much does your manufactured part travel and cost to be painted?
At Productive Plastics, it’s about 100 feet from the manufacturing line to our state of the art painting facility

The manufacturing supply chain can be long and complex. Managing independent suppliers for design, tooling construction, assembly, part painting, and more can be challenging, and each has an influence on the quality, timing, and cost of the finished product.

For custom plastic thermoforming, post-production part painting is a key link in this supply chain. That is why Productive Plastics decided to bring our own painting operation under the same roof as our manufacturing facility.

Our cutting edge painting and finishing facility is solely dedicated to meeting the surface finishing needs of custom heavy gauge thermoformed parts manufactured by Productive Plastics.

What are the Benefits to Our Customers?

Reduced Risk

If a supply chain is only as strong as its weakest link, then strengthening or removing that link reduces the risk of a break. Consolidating the painting and manufacturing operation at Productive Plastics means that there is one fewer supplier to manage and monitor.

Reduced Cost

In-house facilities and complete control over the painting process reduces or eliminates the logistical and quality control costs associated with an off-site supplier.

Reduced Lead Time

The painting facility is located a mere 100 feet from the manufacturing floor which means that parts can be painted, cured, and ready for shipping or assembly in the same day that they are manufactured.

Increased Process and Quality Control

Incorporating a painting facility into the operation at Productive Plastics allowed us direct control of the painting process and quality management.  We implemented the same lean manufacturing techniques, proven processes, and quality controls that we have been evolving on the manufacturing floor for over 6 decades.

Strategically consolidating the manufacturing supply chain is just one of the ways Productive Plastics is constantly improving our ability to contribute to your product’s success. Contact us and give us the opportunity to show you how we can provide much more than a high quality plastic part.

Please contact Productive Plastics for more information on the thermoforming process

Download the New Plastic Thermoforming vs Injection Molding Manufacturing Process Comparison and Selection Guide

Download the Plastic Thermoforming vs Injection Molding Process Comparison and Selection Guide from Productive Plastics

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Part Size Has a Big Impact When Choosing Between Injection Molding and Plastic Thermoforming

Part Dimesion Impact on Plastic Thermoforming vs Injection Molding

When comparing a part manufactured with the heavy gauge plastic thermoforming process and the injection molding process, next to production volume, the largest factor that can impact the cost and even process feasibility is the size of the part.

Essentially, the larger the part is, the more expensive it becomes to produce with injection molding. Comparatively, part size has a very minimal cost effect on plastic thermoformed parts. The breakeven point on cost between the two manufacturing processes, with respect to annual production volume (Deciding Between Plastic Thermoforming and Injection Molding – The Choice is Not Always Obvious), increases as part size increases to approximately 5,000 parts or higher depending greatly on how large the part is.

Why Does Part Size Affect Cost and Manufacturing Process Selection?

 

The injection molding process requires a very large initial capital investment in the tooling and equipment needed to produce a part. This is because the nature of the process involves a very highly engineered 2-sided mold to create a part by feeding thermoplastic resin into a heated barrel with a rotating screw. The screw delivers the raw material forward collecting under pressure the amount required to fill the mold cavity and then injecting into the mold at high pressure and velocity. This action requires highly structured molds and equipment capable of withstanding very high clamping pressure.

As part size and dimensions increase, the complexity of design, engineering, and calibration required to construct, install, and process this 2-sided mold results in a significant increase in the cost of equipment, tooling and setup. The per-part production cost and lead time may also see an appreciable increase as the part size increases requiring much more robust molds and equipment. These increased capital expenditures will result in greater investment and overhead costs calculated in the piece price. Injection molding machines have a limited total mold size capability but can often accommodate multiple parts within the construction of a mold. Smaller part sizes equate to a higher number of parts manufactured per mold and machinery cycle. Larger part sizes decrease the number of parts that can be manufactured per mold and cycle.

Think of a muffin tray with 3-inch diameter muffin molds. Now take that same size tray but with 6 or even 10-inch diameter muffin molds and you imagine the impact on production and cost. In fact, most standard injection molding machines can only accommodate a maximum part size of 4’ x 4’. Larger machinery is available but is also drastically more expensive.

The heavy gauge plastic thermoforming process, on the other hand, involves considerably less pressure and most applications only require a single one-sided tool to produce a part. Additionally, only one part is formed per cycle in heavy gauge thermoforming applications. Consequently, the initial tooling investment is drastically reduced. While an increase in part size will still increase the tooling investment, the impact on cost is substantially less when compared to injection molding. Heavy gauge thermoforming equipment has oven zoning and variable sheet size capabilities which allow for a wide range of part sizes to be efficiently formed from the same equipment investment. The nature of the thermoforming process and flexible capacity capabilities makes scaling production for larger part sizes a relatively easy process. Since most heavy gauge thermoforming operations utilize cell-based manufacturing and CNC part trimming, a larger part can be produced with little impact, other than increased material, on per part cost, cycle time, and lead time. Thermoforming machinery can also manufacture part sizes as large as 10’ x 18’ providing a much larger part size capacity than injection molding.

Large part size infographic

 

Deciding Between Plastic Thermoforming and Injection Molding – The Choice is Not Always Obvious

 

Injection Molding vs Plastic Thermoforming - Deciding when the choice is not obvious

Both injection molding and plastic thermoforming have widespread uses in a long list of industries. Each process has some unique features and benefits that are often advantageous for a specific application. In these instances, the choice to manufacture with plastic thermoforming or injection molding may be very obvious. This is most apparent in production volume. Low to mid volume tends to favor thermoforming, while high volume is usually more cost effective with injection molding.

However, a product’s needs and the capabilities of these two processes sometimes overlap. A part’s geometry may seem better suited for injection molding, but in a limited production run, but it may be drastically more cost effective to manufacture it with plastic thermoforming. This is just one example of an application where deciding between injection molding and plastic thermoforming may not be a clear choice. Selecting the right method in these situations requires a deeper appraisal of the features, benefits, and costs associated with each process.

The Clear Choice

As mentioned above, there are some instances when the type and specifications of an application drastically favor one or the other plastic manufacturing process when the choice is between injection molding or plastic thermoforming.

Injection Molding

Injection molding offers the key benefit of cost effectiveness at the mass production scale. When an application requires the production of more than 3,000-5,000 Estimated Annual Usage (EAU) identical parts with uniform wall thicknesses, injection molding often is the clear choice. This can be attributed to a high upfront tooling investment that is gradually offset by a generally low per unit manufacturing cost. The volume range of 3,000 – 5,000 is due to a variation on part cost in respect to part size. Smaller parts are generally cheaper to manufacture than larger.

  • Part production volumes > 3,000- 5,000
  • Uniform part wall thickness required

Plastic Thermoforming

Plastic thermoforming, on the other hand, has a substantially lower tooling investment and a slightly higher per unit Cost comparison for tooling and parts, pressure forming vs. injection moldingmanufacturing cost. This equates to a much lower total part cost at low to moderate part volumes. Plastic thermoforming becomes the clear choice when the volume of manufacturing is less than 3,000 – 5,000 parts per estimated annual usage. This process also has the capability to produce single parts with very large dimensions, whereas the injection molding process is limited to single part sizes of about 4 feet x 4 feet.

  • Single part dimensions > 4’x4’
  • Part production volumes < 3,000 – 5,000 EAU

Considerations When the Process Choice Is Not Clear

If your part or project doesn’t require a uniform wall thickness, large single part dimension, or has a volume requirement that is in the mid thousands, then you have landed in an area where the capabilities of plastic thermoforming and injection molding may overlap, and your process choice is not so obvious.

The good news is that you are now no longer handcuffed to a process that, while cost or size necessary, may not have the most comprehensive scope of benefits that would contribute the greatest to the success of your project.

Here are some points to consider for each process that can be taken advantage of or avoided now that you are free to choose a manufacturing method better suited to your project’s needs.

Plastic Thermoforming:

  • Large single part capability (maximum dimensions approximately 10’ x 18’)
  • Short lead time ( 6-12 weeks )
  • Able to reproduce injection molded level detail
  • Smaller investment in tooling
  • Lower equipment capital investment leads to lower set up and machine time costs
  • Can produce thinner wall parts than injection molding, resulting in weight savings
  • Greater options for part surface finishing (textures, patterns, distortion printing, painting, etc.) that can be accomplished in the mold.
  • Multi material structures for cosmetic and engineering structure options (e.g. Acrylic/ABS)
  • Variable part wall thickness depending on depth of draw
  • Improved cost effectiveness at lower to mid volumes (< 3,000-5,000)
  • Lighter part weight compared to injection molding for most applications
  • Less molded in stress than injection molding
  • Twin sheet capability for hollow parts and added structure

Injection Molding:

  • Longer lead time (22-24 weeks)
  • Large investment in tooling
  • Cost effective at high volumes ( > 3,000 – 5,000)
  • Efficient material use
  • High level of precise part detail
  • Limited single part size capability (maximum dimensions approximately 4’ x 4’)
  • Finished parts often require post processing painting or finishing
  • Greater design freedom on single wall parts

Want More Information?

What you see above is just the tip of the iceberg when it comes to comparing these manufacturing processes. For more information and for assistance in choosing the right process for your project, please contact Productive Plastics and connect with our industry experts and engineers to see how we can put over 62 years of manufacturing experience to work contributing to your project’s success.

 

Please contact Productive Plastics for more information on the thermoforming process
Please download our complimentary thermoforming design guide for more information on the thermoforming process

Top Plastic Thermoforming Content from 2017

Productive Plastics covered many topics last year on the features, benefits, and capabilities of utilizing the plastic thermoforming process to manufacture custom parts and enclosures for your projects. If you missed any, here is a quick recap, with links to content and data, that we hope you will find informative and useful.

 

Upgrades at Productive Plastic Enhance Plastic Thermoforming Solutions for Your Project

Your Project's Success is our Goal with Plastic Thermoforming

Productive Plastics has been around for 62 years. In over six decades of heavy gauge plastic thermoforming, one of the many lessons we’ve learned is that helping a customer’s project achieve success means a commitment to the constant evolution of every facet of our business. It’s one of our core values.

This year we invested in numerous upgrades. We expanded our resources, expertise, technology, and machinery, all designed to move us further down our technology roadmap as we implement industry 4.0 solutions and capabilities. And we continue to bring you dynamic and comprehensive heavy gauge plastic thermoforming solutions of the highest quality.

Investments at Productive Plastics This Year:

  • More engineering expertise in-house
    • The engineering team grew by 75% this year to provide our customers with top tier technical support, aid in implementing emerging plastic thermoforming innovations, and expand the scope of our value-added services. Welcome to our newest members who joined the engineering team.
      • Bob Cardona – Engineering Manager
        • Engineering team leadership and coordinating implementation of new technologies
      • Don Stiger – Applications Engineer
        • Providing plastic thermoforming engineering support to customers for new projects and part conversions
      • Dan Govender – Applications Engineer
        • Providing plastic thermoforming engineering support to customers for new projects and part conversions
      • Skip Grant – Manufacturing Engineer
        • Overseeing advances in process improvements
      • Bryan Alicea – Engineering Intern
        • Supporting the engineering team and customer on thermoforming applications

Left to right: Bryan Alicea, Don Stiger, Skip Grant, Dan Govender, Bob Cardona

 

  • Additional Sales Support

    John Zerillo

    Yordano Alicea

    • Yordano Alicea has joined John Zerillo, Principal and VP of Sales, in the field as our newest Sales Account Manager. He adds yet another expert resource available to support customers through every step of the product development cycle.
  • New Technology, Machinery, and Process Upgrades on the Manufacturing Floor
    • 4′ x 6′ Advanced Single Station Pressure Forming Machine
      • Advanced controller and sensor system for increased process control
      • Advanced ovens for better consistency in forming
    • 4’ x 6’ Advanced Rotary Pressure Forming Machine
      • Rapid setup time capable
      • Processes plastic material more efficiently
      • Advanced controller and sensor system for increased process control
    • 6 Axis Robotic Arm Cell
      • Automates cell setup for faster operation
      • Removes human errors
  • Process Refinements to In-Facility Painting Operation – Productive Industrial Finishing
  • What are the Benefits for Your Project?
    • Higher Quality and Consistent Parts (tolerances, color, mating points, etc. – whether it’s 2 parts or 2,000)
    • Faster Lead Times
    • Stronger Value at Competitive Investment
    • Comprehensive Solutions
    • A More Flexible and Dynamic Supplier

This year was about laying the foundations for taking our manufacturing processes and value-added capabilities to the next level, to Industry 4.0 and beyond. New machinery, more automation, moving critical processes in-house, advances in technology, and expanded expertise were all added this year to increase our ability to contribute to your project’s success.

We invite you to contact us and schedule a time to tour our facility. We would like the opportunity to show you just how we can contribute to your project’s success and how we can provide much more than a high quality plastic part.

Please contact Productive Plastics for more information on the thermoforming process

 

 

5 Key Points in the Process of Upgrading Parts from Fiberglass to Plastic Thermoforming

Transitioning your product manufacturing process from fiberglass to plastic thermoforming can allow you to capitalize on some major upgrades, benefits, and cost savings for your project. (See some of the advantages of plastic thermoforming vs. fiberglass in a previous post).

However, the process of transitioning from one manufacturing material and process to another, and doing it correctly, may be more complex than simply handing over the existing design and tooling. Below are the basic steps and considerations for the transition process that Productive Plastics has found to help ensure you get the best results from the conversion.

5-key-points-process-of-upgrading-fiberglass-to-plastic-thermoforming

  1. Choosing the right plastic thermoforming manufacturer and process
    1. Plastic thermoforming encompasses a number of sub processes such as vacuum and pressure forming. Consult with your thermoformer to aid in selecting the ideal process for your application. Visit our thermoforming process pages for more information on each process.
    2. Select a thermoforming contract manufacturer experienced in processing a wide variety of material options with a strong understanding of those material properties.
    3. Choose a manufacturer with experience in converting applications from fiberglass to plastic thermoforming to avoid common pitfalls that can delay or increase the cost of the transition.
    4. Strong consideration should be given to a manufacturer with in house design engineers. The onsite expertise will help to ensure a smooth technical transition from fiberglass to plastic thermoforming.
    5. Select a manufacturer that is up to date with best practice methodology such as ISO, Lean Manufacturing, Six Sigma, etc.
  2. Adapting your existing product design to the plastic thermoforming process
    1. Manufacturing techniques, process capabilities, and material properties differ from fiberglass to plastic thermoforming. This is a good thing. The differences are what motivated you to consider converting your product in the first place. These differences will, more than likely, necessitate modifications to your existing design and tooling to meet your product’s needs and to maximize the advantages available with the thermoforming process.
    2. A design engineer, with plastic thermoforming experience, can adapt your product’s design to harness the benefits of the thermoforming process. (Productive Plastics utilizes our experienced in-house design engineers to help our customers with process conversions).
      1. Tighter part tolerances
      2. Reduction in part wall thickness
      3. Complex or aesthetic design enhancements unachievable or not cost effective with fiberglass
      4. Textured surface finish
      5. Lighter weight than FRP
      6. Consistent surface gloss
  1. Material selection
    1. An important consideration when manufacturing a thermoformed plastic part is the selection of appropriate material. There are a multitude of different types of plastic materials, each with their own specific characteristics, properties, strengths, and weaknesses. Communicating your product’s requirements and industry material standards early in the conversion process will allow your thermoformer to assist in selecting the ideal material for the application. Learn more about thermoforming material considerations and options.
  2. Tooling
    1. Properly designed and constructed tooling sets the foundation for tight tolerances and a high quality part. This becomes increasingly more important for complex and multi-part designs. Having your existing tooling evaluated by your thermoforming contract manufacturer as early in the transition process as possible can have a large impact on the lead time of your first part run.
    2. Choose a thermoforming contract manufacturer experienced with tooling materials options and processes to assure the right tool choice for your application and product life.
  3. Prototype testing
    1. Prototype development should be considered with a testing plan that includes dimensional as well as properties evaluation. Engaging in early involvement, support, and collaboration with a thermoforming manufacturer, like Productive Plastics, can aid in creating a successful verification plan.

Productive Plastics is top contract manufacturer for heavy gauge thermoforming, including vacuum forming and pressure forming. Contact us or request our complimentary thermoforming design guide for more information.

Please contact Productive Plastics for more information on the thermoforming process
Please download our complimentary thermoforming design guide for more information on the thermoforming process

Is it time to convert your product to plastic thermoforming?

One of the most common inquiries we receive at Productive Plastics is customers considering plastic thermoforming as an alternative to their current product’s material and manufacturing process.

Is it time to convert to plastic thermoforming

Conversion to plastic thermoforming motivations range from quality and lead time issues with the current manufacturing process to material performance requirements and cost considerations. Just to name a few.

The chances are that if your product is currently utilizing fiberglass or metal for a an application in the medical device, transportation, kiosk, or industrial market, that you are missing out on the performance, aesthetic, weight, and potential cost savings advantages attainable by transitioning to plastic thermoforming.

Continue to check our company blog (Productive Ideas), LinkedIn page, or your inbox over the coming months for information and comparisons on the fiberglass and metal to plastic thermoforming conversion processes.

Regards,
EVAN GILHAM

Temperature Considerations in Plastic Thermoforming Material Selection

Thermal Performance and Considerations in Plastic Thermoforming Material SelectionWhy is temperature an important consideration in thermoforming material selection?

If you’ve ever microwaved last night’s leftovers in the typical plastic to go container, you’ve witnessed the effect that high heat can have on thermoplastic. The plastic begins to soften and lose its stiffness as the material temperature increases and if you heat it long enough or exceed the limit of its operational temperature range, it will begin to distort. Worst case scenario, when you open the microwave door to enjoy your meal, you are presented with something that can be quite unrecognizable from what you put in.

While this example may not be relevant in all cases, it does demonstrate the importance of selecting a plastic thermoforming material with the appropriate temperature properties for your application’s operating environment. Imagine a similar scenario on an essential safety, structural, or functional component for a medical, transportation, or industrial application. Loss of stiffness (flexural modulus) and material distortion (heat deflection) are just a few of the factors to account for when addressing the temperature requirements of a project.

Material considerations for prolonged exposure to excessive temperatures

Most of the effects of temperature to thermoplastic occur at high heat levels, although excessively low temperatures can have an impact as well. Mechanical properties, chemical resistance, electrical conductivity, material fatigue, and many other attributes can be affected by increased temperatures. Below is a list of the most common considerations.

Note: The exact temperature thresholds and performance will vary for each different plastic material. In addition, factors like part geometry and material thickness will also affect material properties under extreme temperatures both high and low. The considerations below are just a general behavior characteristic of plastic in relation to temperature. (reference our article on material testing and data sheets for more information on standard testing of a material’s temperature performance)

Distortion

  1. Exceeding a material’s approximate heat deflection temperature can cause the material to distort.
  2. Prolonged exposure to heat while subjected to a load or force can also cause plastic to deform or “creep” over time.
  3. Most thermoplastic materials have a heat distortion temperature (HDT) of less than 500 degrees F
  4. HDT is a good comparative specification of how different materials respond to the HDT test conditions but provides little information regarding the long term effects of continuous high temperature exposure on their physical, mechanical, thermal, and electrical properties.

Softening

  1. As temperature increases, material stiffness (flexural modulus) will decrease.

Expansion

  1. As with most materials, plastic expands as temperature increases (coefficient of thermal expansion – CTE). This can be a consideration when the plastic is mated with another material, such as metal, that may have conflicting thermal expansion rates.
  2. If the dimensional change is obstructed, stresses can be induced in the plastic part due to excessive tensile, shear, or compressive stress loads that could result in unexpected failure.

Service Life

  1. Thermal Degradation – Plastic materials subjected to prolonged exposure to high temperatures will lose strength and toughness, becoming more prone to cracking, chipping, and breaking, at a rate in proportion to the temperature and time of exposure. Materials exposed to higher heat for longer duration will wear substantially faster than those exposed to more moderate temperatures and exposure times.
  2. The Continuous Use Temperature Rating is based on a thermal aging test that predicts the temperature at which a 50% loss of the original mechanical properties will occur after 100,000 hours of continuous exposure at that temperature. (see table below)

    Continuous Use Temperature Thermoplatic Chart

Thermal Conductivity

  1. The quantity of heat that passes through a cube of the material in a certain period of time when the difference in temperature between the two surfaces becomes one degree.
  2. Plastic materials generally have a much lower Thermal Conductivity than metals. This makes them excellent replacement materials when thermal insulation is important.

Some questions to consider to determine your application’s temperature profile and ideal material candidates

During the product development process, Productive Plastics uses the following questions to zero in on the plastic material options that will be temperature compatible for a customer’s application:

  1. What environmental temperature range (high and low) will the part be exposed to operationally?
  2. What dimensional and stiffness (flexural modulus) tolerances are required of the part at the high, mid, and low points of its expected temperature range?
  3. What loads or forces are expected on the part at the high end of its temperature range?
  4. What is the time/temperature relationship? A low temperature for a long time can result in comparable properties damage as a high temperature for a short time.
  5. What is the projected service life of the application?
  6. Will the plastic part be mated to any other material types, such as metal, as part of the application design?
  7. What are the specified (FST) flame, smoke & toxicity requirements?

Available thermoplastic options and temperature performance

As discussed in previous posts on material selection, when it comes to plastic material options, there are many choices and each has different thermal and mechanical performance properties. The information below will give you a general understanding of the operating thermal ranges of the common plastic material options available.

Note: The options listed are generic plastic material formulations. Many plastic material companies have specific plastic material products formulated and designed to meet the demands of a wide range of industry requirements. For information on the thermal performance of these products, visit our material supplier datasheet page or our thermofoming materials page.

Thermoplastic Material Heat Performance

Click here for a full list of plastic abbreviations and acronyms.

 

Productive Plastics is top contract manufacturer for heavy gauge thermoforming, including vacuum forming and pressure forming. Contact us or request our complimentary thermoforming design guide for more information.

Please contact Productive Plastics for more information on the thermoforming process
Please download our complimentary thermoforming design guide for more information on the thermoforming process

Thermoforming Material Selection (Material Testing and Datasheets Decoded)

When it comes to plastic thermoforming materials, one of the greatest advantages is that they can be manipulated and alloyed at the polymer level as well as being co-extruded to produce a multitude of variations. The result is a large list of available and even customizable plastic material products, each with its own unique properties and often formulated to meet the requirements of a particular industry.

Thermoforming Material Selection Material Testing and Datasheets Decoded

The task of comparing and selecting the appropriate thermoforming material can therefore be daunting. To make the selection process easier, plastic material manufacturers have their material products independently tested to provide potential users with general characteristic and performance data, which is then presented via material product datasheets. These data sheets are excellent for material property comparisons but not always a exact indicator of field performance due to test sample preparation.

See some examples of thermoforming material datasheets here.

This data can give the end user an indication on how that material will behave once thermoformed into a finished component and if it is compatible with their application.

Measuring Plastic Thermoforming Material Properties:

Below is a list of the common tests that are performed on each plastic thermoforming material product, a description of what is measured, and how it should be used to assist in material selection.

Note – The data from raw material testing may not be exactly representative of how a material will perform on your finished product and in the field. Testing performed on material samples is done in a very controlled environment, at a uniform thickness, and as a flat extruded sheet of plastic or often injection molded. Your component, once thermoformed and assembled into a finished product, will likely have complex geometry, varying part thickness, and environmental factors such as temperature that are unique to your application and unaccounted for in standard material testing. For example, a raw material test may indicate a heat deflection (material distortion) of 200 degrees. However, once that same material is thermoformed and assembled on your finished product, it may have a heat deflection of only 190 degrees. So, ultimately, while testing will give you a ballpark indication on how your product will perform, keep in mind that results may vary. For more accurate data, conduct product testing on a finished and fully assembled prototype.

Physical Property Testing

Notched Izod Impact Strength (Ref ASTM D256)

Test definition: Pendulum style impact test of a notched sample subjected to a shock force. Typically used on more notch sensitive materials such as HIPS and ABS. The force absorbed by the notchedsample is measured and the type of failure is described

Material selection application:

  • Good comparison test between similar materials
  • Not a direct indicator of field performance

Specific Gravity (Ref ASTM D792)

Test definition: The ratio of the density of any substance to the density of an equal volume of water. Because Specific Gravity is a ratio it is a unitless quantity.

Material selection application:

  • The Specific Gravity of plastic materials are an indication of their density
  • Higher Specific Gravity will result in heavier material so caution must be taken when estimating and comparing part weights with varied materials

Chemical Resistance (Ref ASTM D543)

Test definition: Evaluation of plastic materials for resistance to chemical reagents (ex. lubricants, cleaning agents, inks, foods) The test includes provisions for reporting changes in weight, dimensions, appearance and strength properties.

Material selection application:

  • The published chemical resistance properties are a good guideline for material selection. However since variable factors can affect chemical resistance one should always test under their own conditions
  • Chemicals can affect strength, flexibility, color, surface appearance, and dimensions of plastics.
  • Plastics often fail even under very low stress when in contact with some chemical agents. This is called environmental stress cracking and is of great importance in material selection

Stiffness (Flexural Modulus) (Ref ASTM D790)

Test definition: Rigidity of material / a measure of stiffness

Material selection application:

  • Provides design criteria to determine the necessary thickness required for a given load
  • Good for comparison of different materials

Hardness (Ref ASTM D2240)

Test definition: A measure of how resistant a material is to various kinds of permanent shape change when a compressive force from a harder body is applied

Material selection application:

  • This is a good measure of resistance to wear by friction or erosion
  • Material resistance to abrasion, chipping, and cracking

Tensile strength (Ref ASTM D638)

Test definition: Resistance to being pulled apart

Material selection application:

  • Tells how material stretches before breaking
  • Provides an indication of overall toughness
  • The most important indication of strength of the material

Dielectric Strength

Test definition: Electrical insulation- the maximum voltage that can be applied to a material without it breaking down

Material selection application:

  • Plastics are generally considered insulators but they can transmit some electrical energy at high frequency
  • Many variables such as material fillers and additives, part thickness, and environmental conditions will affect the plastic’s dielectric constant

Thermal Property Testing

Thermal Conductivity (Ref ASTM E1530)

Test definition: A measure of the ability of a material to transfer heat.

Material selection application:

  • Most plastics are insulators and not good conductors of heat

Coefficient of Thermal Expansion (CTE) (Ref ASTM E831, ASTM D696, and ISO11359)

Test definition: Amount of expansion and contraction at a given temperature

Material selection application:

  • Impact relating to very narrow dimensional tolerances
  • Potential interference and fitment issues when plastic components are combined in assembly with dissimilar material components
  • Tooling and process design considerations are affected by CTE
  • Strict control of temperature during forming, post forming, trimming, and QC processes must be understood and maintained

Heat Deflection (Ref ASTM D648)

Test definition: The temperature at which the material will distort

Material selection application:

  • Usually listed at 2 loading values (264 psi and 66 psi)
  • Lower heat distortion materials will require a greater processing time
  • The temperature up to which rigidity for mechanical loads is retained

Flammability

Test definition: Extent to which a material will support combustion

Material selection application:

  • Plastics made up of organic chemical materials can have violent oxidation reactions in the presence of air at elevated temperatures like any other organic materials such as wood, paper and textiles.
  • Many plastics are now available compounded with flame, smoke and toxicity suppressant ingredients
  • In many applications, government mandated standards will dictate the required testing (See FST testing)

Fire, Smoke, and Toxicity (FST) Property Testing

In industries such as aviation and mass/rail transit, there are very strict regulations on the fire, smoke, and toxicity properties of utilized materials. Many thermoplastic suppliers produce material variations that are specifically designed to meet U.S. and international regulatory requirements. These very industry specific thermoforming material products will typically list the particular industry regulation directly on the material’s data sheet.

Some common industry regulations:

FAR25.853a

FAR25.853d iv & v

ADB-0031

D6-51377

DIN 5510

ASTM E662 & E162

Look & Appearance Property Testing

Accelerated Weathering (Ref Q-Lab)

Test definition: Provides a simulated exposure sequence to ultra violet radiation that allows weatherability to be categorized

Material selection application:

  • The advantage of thermoforming and the use of coextruded material stands out here with the ability to form parts subject to ultraviolet radiation on the outside with a coextruded material that has high weatherability coextruded with a lower cost rigid substrate material
  • Evaluation of color fade relating to time and UV exposure

Scratch & Mar (Ref Taber Method)

Test definition: Provides a measurement of the scratch or mar resistance of plastic sheet

Material selection application:

  • The visual appearance of a scratch or mar normally involves changes in surface topography, color or brightness
  • Some plastic materials have elastic recovery properties that occur after removal of the applied stress

References:

Click here for more detailed information on the testing of thermoplastic properties. (Society of Plastics Engineers – Thermoforming Quarterly 2015 Q1)

For additional information on ASTM standards of material testing, visit the official ASTM website.

You can also visit our Plastic Thermoforming Materials page for more in depth information.

Productive Plastics is top contract manufacturer for heavy gauge thermoforming, including vacuum forming and pressure forming. Contact us or request our complimentary thermoforming design guide for more information.

Please contact Productive Plastics for more information on the thermoforming process
Please download our complimentary thermoforming design guide for more information on the thermoforming process