Regardless of the industry your product serves, whether it includes seating components or wall paneling for bus, rail, or aircraft, requires enclosures or parts for medical devices, or is designed with exterior casings for industrial equipment and electrical components, lightweight material has become essential to creating the ideal product that meets the needs of the end user.
Lightweight offers numerous advantages
Reduced fuel and energy costs – mass of a vehicle has a direct relationship to fuel and energy consumption
Lowered emissions – reduced fuel and energy consumption equates to lower emissions
Reduced maintenance costs – reduction in mass correlates to longer life of components due to less load bearing stress over time (moving and mechanical components, brakes, tires, propulsion systems)
Reduced logistical costs – lighter weight parts are less expensive and easier to install, ship, relocate, or handle
Weight Comparison – Thermoplastic, Fiberglass, and Metal
Lower material specific gravity (mass) means the finished component will be lighter and contribute to a lower overall product weight. There are countless variations and formulations of thermoplastic, fiberglass, and metal materials, each with its own unique specific gravity (details can be found on material manufacturers’ websites and material data sheets). However, if you look at the average weight of some of the most common brands and types of materials available, you can derive some basic comparisons.
Plastic thermoformed parts are 6 times lighter than steel and half the weight of aluminum.
Plastic thermoformed parts are 30 – 40% lighter than fiberglass counterparts.
If reducing your product’s weight is an important factor in your industry, then thermoplastic and the thermoforming process should be a consideration for your current or future projects.
Please download our complimentary material – process comparison guides and conversion guides — for more information. They are full of data that is valuable to decision makers, design engineers and every member of an original equipment manufacturer (OEM) project team
Productive Plastics is more than just a plastic thermoforming manufacturer. We strive to be your advisor throughout the entire product development process by bringing over 60 years of process, design, material, and finishing expertise to assist in manufacturing your component parts and products in the best and lightest way. Contact Us for further assistance or to request a quote.
Deciding Between Plastic Thermoforming and Injection Molding – The Choice is Not Always 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 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, on the other hand, has a substantially lower tooling investment and a slightly higher per unit manufacturing 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.
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
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.
Should You Upgrade Your Sheet Metal Parts and Enclosures to Plastic Thermoforming?
The heavy gauge thermoforming process offers key advantages as an upgraded replacement for many parts currently manufactured from metal. Weight reduction is a key advantage – plastic parts are lighter than metal. Further, custom plastic thermoforming can be used to produce complex geometric part shapes that are not possible with sheet metal at a feasible cost, allowing greater design freedom. This versatility gives manufacturers faster design and production cycles, while also providing the opportunity for innovation with structure and design. Additionally, thermoforming can eliminate the need for secondary part finishing. The industrial market demands lightweight and durable products and high levels of customization, with an eye towards environmental concerns about the use of recyclable materials. Custom heavy gauge thermoforming meets these demands better than sheet metal.
The Impact of Thermoplastics on Industries
Thermoforming can present a substantial upgrade over traditional sheet metal fabrication, metal stamping, metal spinning, and metal casting manufacturing processes and materials. Although sheet metal fabrication exists as a low-cost method for producing parts, the use of sheet metal sacrifices flexibility in design, capabilities, and application. Complex parts manufactured with sheet metal require secondary processes that can involve cutting, bending, welding, and bolting. Producing the same part with thermoforming can eliminate these secondary processes by easily incorporating complex 3D part designs, mating points, and various surface finishes and branding directly into the part’s tooling.
The same differences become apparent when comparing metal stamping, metal spinning, and metal die-casting with thermoforming. Manufacturers use bending and stamping to produce low-cost parts that have a simple geometry. Any attempt to add complexity to a part requires additional assembly steps and cost. The unique process of metal spinning forms complex shapes from aluminum, steel, alloys, and other metals. Rotating a disc or tube of metal at high speeds produces axially symmetric parts and improves the tensile strength of the metal. Metal die-casting produces parts that have high heat resistance, high strength and stiffness, and low thermal expansion qualities.
In contrast, thermoforming provides higher rates of production with a level of detail and complexity that greatly exceeds the capabilities of metal processes. For example, the application of plastic thermoformed enclosures, housings, and covers for medical diagnostic equipment shortens the development and production cycles. Moreover, the use of thermoformed materials establishes lower cost tooling for applications that must comply with global safety standards.
Weight Considerations – Plastic Thermoforming vs. Metal
Plastic thermoforming allows manufacturers to use materials that have a lower density and thinner walls. Both qualities allow weight-conscious industries such as automotive and aerospace manufacturing to achieve significant weight reduction while retaining strength and durability. The use of thermoplastics improves fuel economy and reduces emissions with decreased weight and lowered friction losses in the powertrain. Reducing the weight of gears causes a reduction in inertia and an increase in automotive efficiency. The use of thermoplastics also reduces noise and vibration levels.
For electrical components, the capability to produce strong, lightweight parts also promotes the production of lightweight, wall-mounted or pole-mounted enclosures. Using thermoformed plastics for the electrical enclosures allows easier lifting than seen with aluminum or steel enclosures. When comparing the weights of thermoformed objects to metal objects, noticeable differences exist. With two same-sized objects constructed from polycarbonate and fiberglass, the polycarbonate object weighs approximately ½ pound less. An aluminum same-sized object will weigh twice the amount, an object made from steel will weigh more than six times as much.
The following chart depicts the differences in specific gravity density for different types of thermoplastic and metal materials. Specific gravity equals the ratio of density of the material to the density of water at 39°F. Because the thermoplastics shown in the chart have superior strength-to-weight ratios than the metals, the lighter thermoplastics have equivalent strength and stiffness.
2.55 – 2.80
7.03 – 7.13
Cast Rolled Brass
8.4 – 8.7
7.70 – 7.73
Durability Comparisons – Plastic Thermoforming vs. Metal Manufacturing
Polycarbonate has become a popular alternative for enclosures because of its strength and durability. The durability and impact resistance of polycarbonate allows the use of enclosures in all types of weather and environmental conditions in industries such as oil exploration, agricultural irrigation, wind turbines, and maritime. A polycarbonate enclosure has a tensile strength of 900 pounds per square inch and has a high impact resistance. In addition, polycarbonate enclosures resist damage caused by ultraviolet rays and have high NEMA ratings for dust and moisture protection.
Time and Cost Savings Achieved with Thermoplastics
While a stainless steel enclosure offers the same resistance, stainless steel costs three times more than polycarbonate. The cost comparison between thermoplastics and metals goes beyond direct monetary costs and includes indirect costs such as time. Again, using polycarbonate enclosures as an example, thermoplastics offer the advantage of easy modification. Machining a stainless-steel enclosure requires special tools and additional time.
The weight reduction seen with a polycarbonate enclosure also factors into time and cost savings. Rather than requiring two installers for the attachment of an outdoor stainless steel enclosure, the installation of a polycarbonate enclosure requires only one installer. In addition, the shipping costs for lighter weight polycarbonate enclosures are lower than the shipping costs for metal enclosures.
Direct cost savings with thermoplastics occur through repeatable manufacturing processes that produce less scrap. Given the durability of thermoplastic materials, tools and parts have a much longer service life. Manufacturing costs also decrease because of the design flexibility to consolidate parts and to produce complex mechanisms without secondary processes. Because of the numerous thermoplastic options, manufactures can carefully select materials that optimize manufacturing to production ratios and reduce lead times.
Thermoplastics have replaced the use of carbon steel, stainless steel, titanium, aluminum, magnesium, brass, and bronze in many industrial applications. Along with weight reduction, thermoplastics offer enhanced performance, greater design freedom, and decreased total system costs. Enhanced performance occurs through corrosion resistance, lower friction, increased fuel efficiency, and the capability to handle large loads at higher speeds in harsh environments.
Thermoplastics have become standard materials for parts such as medical diagnostics equipment components, enclosures, fender wells, rear bumpers, seating and interior trim components, window masks, wall paneling, decorative signs, and construction cab interiors. Heavy gauge thermoforming eases the process of manufacturing those components by forming a two-dimensional rigid sheet of thermoplastic into a three-dimensional shape that fits industrial needs and standards. Intricate designs with molded colors and textures occur at lower costs and with faster production cycles.
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.
Choosing the right plastic thermoforming manufacturer and process
Select a thermoforming contract manufacturer experienced in processing a wide variety of material options with a strong understanding of those material properties.
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.
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.
Select a manufacturer that is up to date with best practice methodology such as ISO, Lean Manufacturing, Six Sigma, etc.
Adapting your existing product design to the plastic thermoforming process
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.
Complex or aesthetic design enhancements unachievable or not cost effective with fiberglass
Textured surface finish
Lighter weight than FRP
Consistent surface gloss
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.
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.
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.