Supporting Mobility with High Technology Plain Bearing Solutions


Japanese long-established business Senju Metal Industry Co., Ltd. (SMIC) joins experience, precision and innovative spirit to produce high quality plain bearings with outstanding performance in a multitude of applications connected to the ever-evolving field of mobility.

In April 1938, Senju Lead Factory Co., Ltd was established in Adachi-ku, Tokyo, Japan, as a manufacturer of processed lead and tin products such as lead seals, lead foil, and tin foil. The following year, Senju’s product portfolio was expanded to include solder wire, solder bars, rosin cored solder wire and water pipes. Over the course of the next years, business was continually developed and expanded into other areas, so that in 1944 the company name was finally changed to Senju Metal Industry Co., Ltd. to reflect this diversification.

Today, plain bearings are one of SMIC’s main business areas besides soldering materials and FA equipment. The company is engaged in manufacture of products related to electronics, automobiles and construction machinery.

In order to meet the needs of our customers, production plants and sales offices have been established in Asia, North America, and Europe and SMIC is further developing business to provide high quality and creative technologies around the world.

Decades of experience in plain bearing development and manufacture

SMIC started manufacturing plain bearings in 1952 with the first product being the “Kelmet Bush” for scooters using Kelmet, a copper-lead alloy for bearings. In 1955, bimetal materials made from steel with a sintered layer of leaded bronze were independently developed, and in 1956, mass production of bushings in the same material began. Various bearing products using this bimetal material have been rated highly for their performance, quality and durability, and continue being used by renowned international automobile, construction equipment, and hydraulic components manufacturers. In 1995, SMIC developed and introduced the Clean Metal series, a range of lead-free metal-polymer composite bearings, in reaction to rising environmental awareness. The Clean Metal material CB90 became an instant success and due to increasing demand, SMIC subsequently developed the patented Clean Metal CBE series, which excellent friction characteristics made it popular with shock absorber manufacturers.

SMIC’s plain bearings are developed using the latest technologies for all production steps, including powder sintering, high-precision processing and bonding. The finished product is subject to severe friction and wear tests, and a thorough inspection is conducted to ensure a consistently high level of quality. In addition, a comprehensive quality management system based on IATF16949 certification has been implemented and is applied to all stages of the production process from design and development over verification and manufacturing to improvement.

Metal-polymer composite and bimetal bearings for Automotive applications

SMIC offers two types of plain bearings: “Clean Metal” metal-polymer composite bearings (Photo 1) and bimetal bearings. Metal-polymer composite bearings consist of a porous bronze sinter layer on a steel back, which is impregnated with fluorine-based polymer to achieve a low coefficient of friction (Figure 1). The permittable temperature ranges from -200°C to 280°C. The original polymer layer shows high lubricity and can be used without additional lubrication. In order to meet requirements specific to application, performance and operational environment, SMIC has developed products responding to different needs, e.g. low friction, high load or high rotation, suitable for a multitude of automotive applications including shock absorbers (Figure 2, Figure 4).

Bimetal bearings consist of copper-based metal powder, which is sintered onto a steel back. SMIC has a wealth of experience in providing side plates and valve plates for hydraulic pumps and bushes for undercarriage of construction machinery in this material and is additionally developing lead-free products compliant with ELV Directive and RoHS.

                                              Three layered structure of Clean Metal material (Figure 1)


                                                Examples for Automotive applications of Clean Metal (Figure 2)
Shock absorber sketch with rod guide bush detail (Figure 3)
                                                 Product map (Figure 4)

Expertise in shock absorber rod guide bushes

With shock absorber rod guide bushes accounting for almost 40% of SMIC’s plain bearing sales, the company has especially rich experience in this field and cooperates with customers to develop new and innovative materials to meet specific requirements.

Shock absorbers are responsible for damping shocks and vibrations that occur when tires capture irregularities in the road surface. The rod guide bush supports the shaft of the shock absorber and is the first component to dampen shock and vibration (Figure 3). By choosing the material according to the required performance, Clean Metal bushes contribute to a comfortable ride by adjusting the damping force through specified friction characteristics.

The preferred damping performance varies depending on vehicle type and personal preference of the driver. In order to meet diverse needs, SMIC continues to develop new materials using the latest technology backed by extensive experience and expertise in the industry.

Should you be interested to learn more, please do not hesitate to contact SMIC’s European Sales office Senju Metal Europe at or +49 (0)69 29 80 15-0.