SIC 3061

This category covers establishments primarily engaged in manufacturing molded, extruded, and lathe-cut mechanical rubber goods. The products are generally parts for machinery and equipment. Establishments primarily engaged in manufacturing other industrial rubber goods, rubberized fabric, and miscellaneous rubber specialties and sundries are classified in SIC 3069: Fabricated Rubber Products, Not Elsewhere Classified.

NAICS Code(s)

326291 (Rubber Product Manufacturing for Mechanical Use)

Industry Snapshot

Molded, extruded, and lathe-cut goods are used in various types of machinery and equipment. End uses for these products exist in automobiles, oil and gas equipment, appliances, farm equipment, and construction machinery. About 600 firms in the United States make molded, extruded, and lathe-cut goods. Due to the diversity of end uses, the market is fragmented and no single company has dominated the industry. The sector also faces strong foreign competition.

According to U.S. Census Bureau, the value of shipments for this industry in 2000 was $7.7 billion, and the number of employees totaled 60,447 (of whom 48,698 were production workers).

Many of the products in this segment are custom-made to various end-user specifications. As such, manufacturers often sell them with a higher profit margin. Such customer orders have helped this sector show a higher rate of growth in shipment value compared to other industries.

Entering the late l990s, the recovery of the U.S. automobile industry began to fuel growth in industrial rubber products, which find more than half their end uses in cars. Other areas of growth in the early 2000s were expected to be manufacturing, mining, construction, oil and natural gas, appliances, and agriculture.

Competition from imports and other materials such as plastics, which cut processing time by eliminating the curing step necessary to rubber production, were expected to hold back overall growth. As automakers continue to ask for just-in-time delivery to decrease inventories, the advantage of plastics provides a competitive edge in some uses.

Background and Development

The term "molded goods" encompasses a wideranging group of products whose shape is determined by the mold in which they are produced. Markets using molded goods include automotive and other types of transportation, appliances, oil and gas fields, off-highway machinery, and equipment used in such industries as construction, farm, lawn and garden, and mining. Benefits of molded goods include resiliency, insulation, cushioning, flexibility, and vibration or noise dampening.

Among the myriad of products produced in this segment of the industry are automotive and off-highway air springs; chassis bumpers; engine and truck mounts; automotive vibration dampers; weather-stripping; wiper blades; pedals and pedal pads; rubber marine bearings; bellows, grommets, and mounts used in appliances; drill pipe protectors; shock absorber mounts; conveyor wheels; pool table bumpers; and railroad-crossing pads.

The rubber mold, normally made from steel, is the most important component in the molding process, giving the part its shape and ensuring that it has the proper dimensions, look, and functions. The choice of molding process—compression, transfer, or injection—takes into account many variables because none of the three main methods can handle all applications. Some hybrid processes, combining two of the three molding techniques, have become popular in some uses.

Due to its relative simplicity, compression molding is the most widely used technique. The material is placed in the mold and compressed using hydraulic clamp pressure. When the cycle is completed, the clamp is released and the product removed from the mold. The mold can be virtually any size as long as sufficient clamping pressure exists. This process generally has the least-expensive mold and yields minimal amounts of waste rubber. Drawbacks include having the longest cure time (the cycle it takes for the product to be formed), the number of finishing operations necessary to render the product usable, and the lack of control over meeting exact customer specifications.

Transfer molding is a more precise process. The material is transferred from a pot, normally located above the mold cavities, down to the mold at the desired time. The technique gives better tolerance control, ensures the mold is closed before rubber is introduced to eliminate exposure to the environment, can be used when other items are to be inserted into the rubber product, and sometimes offers a substantially shorter curing time. Transfer molding, however, leaves more waste, requires moderate secondary operations, and requires a more expensive mold.

Injection molding requires the most expensive press and molds, but often yields the lowest overall cost to produce the part, as it gives more options for automation. Material is injected into a closed mold from an injection barrel. One injection system can be used to feed material into several molds, either by having the injector automatically moved to different molds, or by having several molds rotate to a fixed injection unit. The part removal operation is also a good candidate for automation. Other benefits include high-precision parts, lowest rubber prepping cost, shortest cycle times, and minimal exposure to the environment during the molding process. Drawbacks to injection molding include expensive tooling and the potential for large amounts of waste if proper precaution is not taken.

An extruder is a power-driven screw enclosed in a cylinder. In the extruded molding process, material goes in one end and is sent through the cylinder by a rotating screw. At the other end, the material is fed through a die, which is a steel mold designed to produce the desired shape of the product being made. Among the products made using extrusion are cables, wire insulation, door and deck automotive lid seals, window and glass channels in cars, wiper blades, and rubber tubing used in medical, automotive, and appliance applications.

Extruders have been in use for more than 150 years in industry. Originally, the rubber going into the extruder had to be prewarmed so it could be conveyed through the extruder. This hot-feed extrusion method was time-consuming and required great amounts of labor to complete the warming process.

Earlier in the twentieth century, however, cold-feed extruders were developed. These machines accept material at room temperature and include components designed to warm and soften the material for final forming. These machines are sometimes three times longer than hot-feed extruders, but they result in faster cycles, lower labor costs, and more uniform products. Extruded goods are flexible and good for sealing. They offer the advantage of low-cost permanent tooling and high production rates. Extrusion dies to make prototypes can be produced swiftly and for little cost. Recent studies have emphasized new designs for more effective self-feeding of the material and higher output rates.

While non-automotive, lathe-cut goods are the smallest segment of the industry, automotive lathe-cut goods represent a larger segment. Lathe-cut products in the automotive industry include oil filter washers, fuel system components, disc brake washers, and electric and electronic parts. Other areas using these goods are agriculture, communications, filtration, material handling, printing, and pumps and valves used in water systems.

Current Conditions

As automakers remain the single largest customer of molded, extruded, and lathe-cut products, their demands have a large impact on the industry. During the late 1990s, for example, it was common for manufacturers to reduce their supplier base. While in the past an automaker may have bought a single part from many firms, the same company is now more selective in vendor selection, buying parts from fewer and fewer vendors. Auto companies became more stringent in their requests for high quality, on-time delivery, quick response to requests, and, as always, competitive pricing.

Automakers also began to ask suppliers of these products to provide the technical capability to develop a component from conception to finished product. This enabled vehicle manufacturers to cut their own development overhead and leave certain design work to companies with expertise in that particular discipline. Full-service molders and extruders, therefore, were expected to make the most gains.

While there have been an increasing number of companies in this industry gaining size, industry executives agree that there will always be a place for the so-called "job shops," which do custom work on products that often are short-run. These firms offer quick turnaround on prototypes and fill niche markets that larger molders cannot service cost-effectively. Job shops are often run by entrepreneurial types, carry lower overheads, and are highly flexible. One government study found those single-establishment companies with up to 20 employees accounted for 7 percent of the total value of shipments in this category.

Growth prospects for U.S. consumption of molded goods has been reasonably healthy. Areas expected to remain strong in the early 2000s are transportation, off-highway machinery, appliances, and other miscellaneous applications—all above 6 percent a year. Capital spending in these areas increased significantly during the economic boom of the late 1990s.

Growth in molded products for oil and gas machinery is expected to lag behind, at just 2 percent a year—in part because of a drop in U.S. oil production, and only a slight increase in natural gas production.

Other areas in which strong growth is anticipated include certain niche markets such as wiper blades and vibration control products, extruded rubber products, automotive extrusions, weather stripping, and lathe-cut goods.

Technology is evolving, however, to a future in which cars will have adaptive or active vibration control systems. Computer-controlled actuators and sensors will be used in conjunction with the rubber mounts, allowing the product to adapt to numerous frequencies.

Industry Leaders

Because of the fragmented nature of the industry, no one firm or small group of firms dominate. Several companies do, however, have a substantial presence.

The Cooper Tire & Rubber Company, based in Find-lay, Ohio, is a major supplier of molded goods for automotive vibration controls. The company had sales in 1999 of $2.2 billion and employed more than 10,000 workers. Aeroquip Corporation/Automotive Group, located in Maumee, Ohio, manufactures hoses and fittings for the automotive industry. Estimated sales in 1999 were over $500 million. GenCorp, Corporate Technology Center, located in Akron, Ohio, is the automotive products subsidiary of GenCorp Inc., based in Rancho Cordova, California. The company overall had sales of $1.7 billion in 1999 and employed more than 10,000 workers.


The mechanical rubber goods industry employed 60,447 workers in 2000. The number has been growing slowly but steadily since 1990. The average hourly wage in 2000 was $12.47, somewhat below the average for the manufacturing sector as a whole.

America and the World

Imports from Europe and the Far East have played a significant role in the market. Some U.S. firms, in turn, explored service niches or specialty markets that have traditionally been harder for imports to penetrate than markets for commodity products.

Joint ventures, especially with Japanese-owned companies, also became prevalent. These helped U.S. firms gain business with both foreign automakers as well as transplant companies that make cars and other products in America.

Research and Technology

Plastic products are expected to continue to challenge rubber for end-product applications that require more stringent characteristics. As automakers design smaller engine compartments in an effort to improve fuel efficiency and work in conjunction with front-wheel drive systems, they will demand better-performing products. As smaller compartments lead to hotter engine temperatures, automotive components will need to be made of materials with higher heat tolerances.

While traditional rubbers have continued to be used, other materials have been tested. Specialty elastomers, a synthetic rubber made for such specific uses, and thermoplastic elastomers, a material that is processed like a plastic but has the properties of rubber, are among the materials vying for increased usage. New fuels, mandated to reduce harmful emissions into the air, will also factor into material selections in the future.

New techniques will continue to evolve. One such predicted growth area is liquid injection molding (LIM) using silicone rubber. This process was unveiled in the late 1970s amid much hype as to how it would simplify life for molders. According to early literature, the liquid material went directly into the machine and the finished product came out—supposedly eliminating the need for several secondary operations necessary with traditional rubber molding.

While the reality of LIM did not quite meet its promise when it was first introduced, improvements in its technology in the early 1990s increased its popularity. Molders of components for medical devices, especially, adopted the process, with many adding or expanding LIM capability. The draw for medical molders has been the ability to make a clean product—the finished component emerges virtually untouched—that meets tight tolerances.

Cellular manufacturing has also gained in prominence. In this process, molding and secondary finishing operations all take place in one "cell," eliminating the necessity for the product to be moved to different areas of the plant. This improves quality, product flow, and efficiency, and helps reduce staffing requirements as well.

A new fully integrated system for high-yield molding of trimless/flashless parts is the industry's newest technology, developed by Hull/Finmac Inc. in Warminster, Pennsylvania, and Trimless/Flashless Design Inc. (TFD) in Chantilly, Virginia. The system is a combination of a 35-ton compression press and a unique modular mold, a first for the rubber industry. The system's purpose is to reduce scrap rates and eliminate most deflashing operations, improving speed and quality in molding natural or synthetic rubber.

Industry products themselves are expected to continue to evolve. One such area is in the field of vibration control products for automobiles, which have traditionally been passive systems. With use of a rubber mount, engineers can control a single frequency that causes noise or motion of the vehicle. More advanced mounts have been designed to control two frequency-related problems.

Technology is evolving, though, to a future where cars will have adaptive or active vibration control systems. Computer-controlled actuators and sensors will be used in conjunction with the rubber mounts, allowing the product to adapt to numerous frequencies.

Further Reading

"Advanced Elastomer Introduces New TPE." Rubber and Plastics News. 13 November 1995.

Darnay, Arsen J., ed. Manufacturing USA. 6th ed. Farmington Hills, MI: Gale Group, 1999.

Long, Harry, ed. Basic Compounding and Processing of Rubber. Akron, OH: American Chemical Society Inc. Rubber Division, 1995.

Smith, Maurice, and James F. Walder, contributors. The Vanderbilt Rubber Handbook. Norwalk, CT: R.T. Vanderbilt Co. Inc., 1990.

"Technology Focus: Integrated System for Rubber Molding." Mechanical Engineering, September 1996.

United States Census Bureau. "Statistics for Industries and Industry Groups: 2000." Annual Survey of Manufacturers. February 2002. Available from .

User Contributions:

Comment about this article, ask questions, or add new information about this topic: