02. Producing products Sustainability

Summary

  • We introduce three strategies for reducing resource usage in product manufacturing:
    1. Reducing the volume of materials used
    2. Saving steps from production processes
    3. Reusing material wastes
  • The volume of material used to produce products can be reduced through techniques such as shape optimization, integration of multiple components and product miniaturization. We present a practical case study in the use of resin CAE technology for product shape optimization.
  • Streamlining production processes as much as possible by saving processing steps associated with tasks such as assembly and painting can reduce labor costs (personnel costs), cut energy consumption, and minimize material losses. We present case study examples in which materials are chosen to enable easily-assembled product shapes or save the need for painting.
  • Wastes of resin materials from production processes may be collected and finely ground to yield a reused resin substance known as regrind, which may be blended with “virgin” resin at certain concentrations to reduce overall resin use. We present materials offering good thermal stability that are ideal for use as regrind.

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Reducing resource usage in product manufacturing

In recent years, the increasing ubiquity of slogans like “circular economy” and “carbon neutrality by 2050” have left many manufacturing engineers and production-process designers wracking their brains to devise strategies for sustainable manufacturing with reduced environmental impact.

 

One strategy for manufacturing products in more environmentally-responsible ways is simply to reduce resource usage. This is not a new idea—indeed, some time ago it was enshrined as the first of three exhortations in the widely circulated slogan “reduce, reuse, recycle.” Below we discuss three strategies for reducing resource usage in product manufacturing.

Three strategies for reducing resource usage:

  1. Reducing the volume of materials used:
    Apply shape-optimization and miniaturization techniques to reduce the weight of products (i.e., the volume of material used to produce each product). Decrease the component count to reduce overall material usage.
  2. Saving steps from production processes:
    Reduce the component count; adopt integrated, monolithic architectures; and design product shapes to streamline assembly processes, thus reducing the number of processing steps required to assemble products. Use good appearance materials to save painting steps.
  3. Reusing material wastes:
    Material fragments that would previously have been discarded are reused as regrind to reduce overall material usage.

Reducing material volume and saving processing steps

The products we use in our daily lives—from household appliances to cars—are composed of many components, and they are produced via complicated processes involving many steps, from component molding to product assembly and painting.

 

Reducing the number of processing steps to the bare minimum can cut labor costs (personnel costs), save energy in post-processing steps, and minimize losses of constituent materials. Other ways to reduce resource usage in manufacturing include using smaller quantities of resins to produce each product, and saving paints.

(1) Reducing the volume of material used

A. Reducing the number of components and applying shape optimization and miniaturization to reduce the amount of resin used to produce each product

By optimizing the shape of products, it may be possible to reduce the number of components—for example, by adopting monolithic, integrated architectures to replace assemblies of multiple components—and to reduce the size and weight of products. Computer-aided engineering (CAE) for resin materials is a powerful tool for determining optimal shapes for product designs.

 

B. Choosing materials that require no painting

Choosing materials with weather-resistant and good surfaces, or materials capable of expressing metallic coloration without painting, can save painting steps from production processes and reduce use of plating materials and solvents. This also helps to advance the goal of item (2) below by saving processing steps.

(2) Saving processing steps

 A. Design product shapes to streamline assembly processes

Compared to metals, engineering plastics offer significantly greater shape flexibility, allowing product designs to be optimized for maximal ease of assembly. Products that are easy to assemble not only save assembly steps in production processes but may also obviate the need for certain screws and bolts, helping to reduce resource usage.

 

B. Choose materials with good formability properties to save post-processing steps

Some product-manufacturing processes require secondary processing steps, such as burr removal or annealing to repair warping or strain. Choosing materials with less susceptibility to warping or burr formation may save the need for such post-processing steps.

Reusing material wastes

Manufacturing processes using resin materials tend to generate material wastes such as sprues and runners, which accumulate at production sites. When these resin wastes are collected, finely ground, and subjected to molding and formation, they are known as regrind. In general, as long as regrind does not exhibit any degradation in relevant physical properties, it may be blended, at a certain concentration, into new resin (known as “virgin’’ resin). (Needless to say, regrind cannot be used in all situations, and in general the question of whether or not regrind can be usefully reused is highly situation-dependent.)

 

Making effective use of regrind—material that would otherwise be discarded—can help to reduce the total quantity of resin required to manufacture a given product.

Three strategies for reducing resource usage

Three strategies for reducing resource usage

Asahi Kasei’s Recommended Solutions ①

Reducing component counts and saving process steps

SunForce™ modified PPE foam beads offer greater flexibility in designing products

SunForce™ combines the excellent properties that only foams can offer—light weight and thermal insulation—with flame retardance (UL-94 V-0), dimensional stability, and the ability to form products with thin walls. SunForce™ is a foam material offering functionality far beyond the capabilities of conventional foams. This material exhibits exceedingly small dimensional variations in processing and offers formability properties nearly equivalent to those of typical injection-molding materials, making them ideal for worry-free use in applications such as structural bodies and equipment chassis, where high dimensional stability is essential.

 

SunForce™ also features the unique strengths of PPE resins—specifically, low coefficients of linear expansion relative to other resin materials—and remain relatively unaffected by temperature fluctuations.

 

SunForce™ is produced by filling beads in tooling and applying steam to induce swelling in these beads, resulting in thermal bonding. Thus, in contrast to injection molding—in which resin is injected into a tooling at high temperature and high pressure—the SunForce™ process tends to produce minimal warping and few sink marks in finished products, even for products with spatially-varying wall thicknesses. This saves the need to impose shape constraints—such as uniform wall-thickness requirements—offering greater flexibility in designing products.

 

Exploiting this flexibility—for example, by fabricating molded products with shapes conforming to substrates or harnesses—may, in some cases, save the need for screws or bolts to fix components in place when assembling component packs, simplifying production processes.

Metallic-colored POM materials save painting steps to cut costs and reduce environmental impact

Polyacetal (POM) features excellent mechanical properties, sliding behavior, and chemical resistance, and is used for many structural components and internal components.

 

Asahi Kasei’s TENACTM-C ZM413 POM resins are metallic-colored POM copolymers with physical properties and weather resistance equivalent to those of standard weather-resistant grades. This material also complies with various automotive OEM regulations restricting the emission of volatile organic compounds (VOCs) for materials intended for use in automobile interiors.

 

Typical methods for imparting metallic finishes to products involve painting or plating on the surface of the base resin. However, such approaches are costly due to the multiple processing steps they require—and have the additional drawback of polluting the environment through the use of solvents at various stages. We recommend to choose TENACTM-C ZM413 which may save these drawbacks by omitting painting steps from your production process.

Details on metallic-colored POM resin TENACTM-C ZM413 available here.

Weight reduction by replacing metal to plastic & optimizing parts design through the use of resin CAE

Asahi Kasei has in-house expertise in resin computer-aided engineering (CAE), a set of analytical techniques developed specifically for designing resin products. To illustrate how this techniques are used in practice, we introduce the case study application depicted schematically in the figure below.

 

The original product (far left image) was made of steel and consists of multiple components. We used CAE technology to perform a topology-optimization analysis (intermediate images), resulting in a final design proposal in which the product was made from resin instead of steel (images at right) and achieved a weight reduction of more than 80% compared to the original design.

 

In this case, taking advantage of Asahi Kasei’s resin CAE technology allowed the designer to identify the most efficient distribution of materials within the established design space, subject to the structural limitations and loading and constraint conditions relevant for the scenarios in which the product was expected to be used.

 

Moreover, the shapes produced by topology-optimization analysis are extraordinarily flexible; in the case study depicted here, this freedom—together with the skill and experience of the engineer performing the analysis—produced an innovative injection-molding design featuring a totally novel shape unlike any existing design and, indeed, beyond the confines of any existing design paradigm. Further investigation revealed superfluous regions of the proposed design; saving these further simplified the shape of the product, ultimately succeeding in decreasing the number of components and dramatically reducing the weight of the final product.

 

To learn more about case study of topology optimizarion of brake pedal bracket, you can download slide here.

Topology-optimized design

Case study: Replacing metal hinges with high-strength, good appearance polyamide that require no painting or plating

Hinges, used primarily for doors, must be high-strength components and are thus typically made of die-cast metal. However, making attractive hinges typically requires decoration via plating—a process that generates waste water containing metal ions, whose disposal entails heavy environmental impact.

 

Asahi Kasei’s LEONATM SG series of polyamide resins not only satisfy all performance requirements demanded for hinges, but also yield attractive final products without painting or plating, slashing overall weight and reducing waste to lessen the environmental impact of the manufacturing process.

 

To learn more about LeonaTM S Series, you can watch webinar recording here.

Case study: chassis for air-pressure regulators, replacing metal with high-strength polyamide saves post-processing steps and yields lighter-weight products, reducing shipping-related energy consumption

Air-pressure regulators are key components installed at many product-manufacturing sites. Because the chassis bodies in which these instruments are enclosed must have a high strength, they are typically made of metal. On the other hand, because the regulators incorporate networks of fine-grained flow pathways to control air flow, their production consumes significant quantities of energy and entails heavy material losses. Switching from metals to Asahi Kasei’s high-strength LEONATM S series of resins saved the need for post-processing steps, helping to streamline production processes.

 

 

Also, because air-pressure regulators are shipped to customers around the world, the reduction in product weight achieved by replacing metals with resins significantly reduced shipping-related energy consumption.

 

To learn more about LeonaTM S Series, you can watch webinar recording here.

Asahi Kasei’s Recommended Solutions (2)

Reusing product wastes

XYRON™ modified PPE resin are excellent for regrind

XYRONTM modified PPE resins are materials that offer excellent thermal stability and hydrolysis resistance, and exhibit minimal degradation in physical properties when used as regrind, making them easier to reuse than other resins. This material also boasts the lowest specific gravity of all engineering plastics; its light weight helps to reduce the volume of material used in manufacturing.

 

Exploiting these properties by using modified PPE resins to manufacture products—and reusing sprues, runners, and other wastes produced at manufacturing sites—allows you to reduce total material usage and minimize environmental impact.

 

Note: In cases where the external appearance of products is important, impurity contamination due to the use of reused materials can produce defects that result in unattractive products. Avoiding this situation requires carefully optimizing the percentage of reused material used; as a rough guideline, we recommend considering percentages of 20% or below.


We would like to talk to you about Asahi Kasei’s sustainability solutions. Please contact us to ask questions and request samples. We look forward to hearing from you!

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