A Deep Dive into Sourcing Automotive Plastics

For the longest time, alloys have dominated the overall buy and material content of an automobile. However, in the last decade, due to regulation and fuel prices, there has been a major shift to using lighter weight materials, most notably plastics or composites. This rise in the automotive plastics market is primarily due to the industry’s push to reduce the overall mass of an automobile, which is ultimately being driven by federal regulations and standards (CAFE), and fuel costs. This trend is only going to accelerate as the global automotive plastics market is expected to grow at a CAGR of 13% by 2020.

The growing global demand for automobiles from emerging economies such as China, India, and Latin American countries are poised to drive the total market growth. The Asia-Pacific region has dominated the overall market share of automotive plastics in terms of volume, as well as revenue, since 2015, followed by Europe and North America.

Key factors restraining the automotive plastics market are high material cost and the requirement of a significant investment in material research activities. Currently, these restraints act as barriers to further market growth. The utilization of new advanced materials in automotive designs requires new manufacturing technologies and their use in manufacturing new components involves process re-engineering, which incurs large capital cost.

A procurement professional must always keep the following considerations in mind, before making a critical plastics sourcing decision. Not only do all of the following affect the overall pricing of the component, but equally as important, they affect the quality.

Key Considerations

Automotive plastics offer up unique and useful properties such as toughness, durability, recycle-ability, thermal stability, resilience, resistance, design flexibility, and light weight (that certain alloy materials cannot claim). The most common applications for plastics in automobiles are with the interior, exterior and engine components because they offer a lighter-weight option, thus increasing fuel efficiency. Plastics also improve the look or aesthetics, reduce noise and vibrations (NVH), insulate, etc. Not to mention, plastics offer the automotive industry a cheaper alternative to a component with color without having to use paint and other potential coatings. Plastics also offer a more sustainable approach to a more sustainable automobile. There is an increasing demand for biodegradable varieties such as starch-based, PHA-, PLA-, PCL-, and PBS-based plastics. Depending on the material chosen, cost will be affected. A procurement professional must keep this in mind while sourcing. They may work for a very environmentally-conscious company who is looking for regrind and biodegradable material, however, the impact of higher prices based on current availability also needs to be considered.

Application & Volume

A procurement professional must work hand-in-hand with the engineering team to clearly understand the application of the plastic component. This will affect which processes and materials are chosen for the application. One must always ask the team, “Can this component be made of plastic as opposed to an alloy?” It is critical for the procurement team to be involved in this aspect because they should be fully aware of all plastic production processes (provided in more detail, below) so they can have a say in recommending a process and even challenging engineers. For example, injection molding a component is usually recommended in higher volume programs and offers a lower overall piece cost, yet yields a higher tooling cost; whereas thermoforming usually offers lower tooling costs and a higher piece cost. Based on the process chosen, there are certain limitations that the various processes offer based on the application and volume. A procurement professional should then choose a preferred process and source a supply partner, based on their knowledge of program application and volume.

Process

To properly source an automotive plastic component, a procurement professional must consider and fully understand the process that the component and application warrant. Many factors determine which process is acceptable. These include size, weight, shape, application, location, heat, flow, etc. The most popular plastic processes for automotive applications, include the following:

Injection Molding

Injection molding is the most popular process used for automotive plastic components. With this process, the plastic (in pellet form) is placed into a hopper which feeds the plastic pellets into a heated injection unit, where it is pushed through a long chamber. The material is liquidized during this process and hardens after drying. For high-volume plastic component programs, this is the recommended process.

Thermoforming/Vacuum Forming

Thermoforming uses a plastic sheet, which is formed with a mold by applying air or through mechanical assistance. The air pressure used can be nearly zero psi, or several hundred psi. At 14 psi, which is approximately equivalent to atmospheric pressure, the pressure is created by evacuating the space between the mold and the sheet. This is known as vacuum forming.

Blow Molding

When the component needs to be, hollow or have flow-through, the blow molding process is most beneficial for the application. A molten tube is created with blow molding by using compressed air, which blows up the tube and forces it to conform to the chilled mold.

Compression Molding

Compression molding is the most common process used with thermosetting materials and is usually not used for thermoplastics. With this process, the material is squeezed into its desired shape with the help of pressure and heat. When the mold is closed and heated, the material goes through a chemical change that causes it to harden into the desired shape. The temperature, pressure, and length of time utilized during this process depends on the desired outcomes.

Extrusion

The process of extrusion is usually used to make products such as film, continuous sheeting, tubes, profile shapes, rods, coat wire, filaments, cords, and cables. As with injection molding, dry plastic material is placed into a hopper and fed into a long heating chamber. At the end of the chamber, however, the material is forced out of a small opening, or a die, in the shape of the desired finished product. As the plastic exits the die, it is placed on a conveyor belt where it is allowed to cool. Blowers are sometimes used to aid in this process, or the product may be immersed in water to help it cool.

There are other processes that are gaining ground in the automotive plastic industry, such as Reaction Injection Molding (RIM) and liquid casting, however, being fully aware and knowledgeable of the above processes will give a procurement professional confidence going into a sourcing decision for a plastic component.

Material(s)

Based on the application of the component, its proximity to a heat source, location on the vehicle, and process, there are a variety of high performance plastics that are widely used in the automotive industry, and a sourcing professional must consider the characteristics of each when sourcing a plastic component. The most common automotive plastic materials that must be understand include:

Polypropylene (PP)

Polypropylene is the most common used plastic formulation in the automotive industry and accounts for more than share of the automotive plastics market. The benefits of this material include it being rugged and unusually resistant to many chemical solvents, bases, and acids. The most common automotive applications for PP include bumpers, tanks, insulation, and carpet fibers.

Polyurethane (PUR)

Polyurethane is another very common material used in automotive applications and accounts for roughly 17% of global consumption. It is an elastomeric material that has a broad range of hardness. The benefits of this material include toughness, flexibility, along with resistance to abrasion, temperature, and most solvents. The most common automotive applications for PUR include foam seating and cushions, foam insulation panels (NVH), tires, bushings, and electrical components.

Poly-Vinyl-Chloride (PVC)

Components using this material can be extruded, injection molded, compression molded, calendared, and blow molded to form a wide variety of products, either rigid or flexible depending on the amount and type of plasticizers used. The benefits of this material include flexibility, flame retardance, thermal stability, high gloss, and low lead content. The most common automotive applications for PVC include instrument panels, wire sheathing, pipes, and door panels.

Acrylonitrile Butadiene Styrene (ABS)

Acrylonitrile Butadiene Styrene is a copolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The styrene gives the plastic a shiny, impervious surface. The butadiene, a rubbery substance, provides resilience even at low temperatures. A variety of modifications can be made to improve impact resistance, toughness, and heat resistance. The most common automotive applications for ABS include body components, dashboards, and wheel covers.

Polyamide (PA, Nylon 6/6, Nylon 6)

Nylon 6/6 is a general-purpose nylon that can be both molded and extruded. Nylon 6/6 has good mechanical properties and wear resistance. It is frequently used when a low cost, mechanically strong, rigid, and stable material is required. Nylon is highly water absorbent and will swell in watery environments. The most common automotive applications for PA include gears, bushes, cams, bearings, and weather proof coatings.

Other plastic materials, like Polycarbonates (PC) are increasing in popularity for automotive applications. The PC segment is projected to witness the highest CAGR of all plastic materials at 12.4% by 2020. Also, newly developed material technologies are making waves in today’s automotive market and a procurement professional should understand the pros and cons of these, as well. Some of these technologies include reinforced composites, most notably Poly(methyl methacrylate) (PMMA), and carbon fiber. The carbon fiber technology, while still a very manual and expensive process, is gaining a lot of traction in automotive body applications due to its strength and lightweight benefits. For example, the new Ford GT consists of a full carbon fiber body, which minimizes the full vehicle weight and adds tremendous strength, sleek aerodynamics, and stunning aesthetics. It is only a matter of time until this technology becomes more efficient and is used on larger production programs.

Conclusion

The automotive plastics industry is positioned to expand exponentially in the coming years. Understanding the above key considerations will ensure confidence in sourcing decisions and offer companies a competitive advantage in making critical future decisions. Also, being aware of environmentally-friendly materials and new technologies is essential for advancement and future success. Though these considerations maybe simple, there are many procurement professionals today making key decisions without considering all potential options when it comes to plastic processing and material selection. A resourceful procurement professional will spend the time it takes to fully understand plastic applications, volumes, processes, and materials prior to sourcing to best position their companies for supply success.

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