Motion systems applications: Chains for all environments

By Leslie Langnau • With recent advances in precision, designers can use chains in more applications than ever, including remote installations thanks to lubrication technology.

Chains are versatile and reliable components used primarily to transmit power in machinery or convey products. Roller chains are mainly used with drives. But they can also be found in applications with harsh environments that subject chain to weather, water or chemicals, where other options would fail.

The Titan Series Chain from U.S. Tsubaki Power Transmission incorporates features of Tsubaki’s standard ANSI chain with new features for extended life performance. These chains use a specific chain construction that includes special coated pins and pin links, black oxide roller link plates, G7 Solid Bushings (Performax Lube Groove – sizes 80-140), and ring-coined connecting links. This combination enhances durability and strength for longer chain life.

Most drive applications use an ASME/ANSI roller chain wrapped around a driver sprocket that is connected directly to the motor or reducer. This sprocket is usually connected to a machine’s conveyor head-shaft. More after the jump.

VarioFlow plus flexible-chain conveyors from Bosch Rexroth offer a number of standard options for a variety of application requirements with maximum interchangeability and modularity. With low-noise operation, the chain-conveyor system also comes in a stainless-steel version with other FDA-compliant materials for the food industry. Rexroth also offers a workpiece-pallet version suitable for transporting pallets in electronic and automotive industries.

Conveyor chains are used in applications that require moving product horizontally, vertically or around curved radii. Most common conveyor chains are ASME-style (ANSI-style) attachment chains. Types include single-pitch attachment chain, double-pitch attachment chain, hollow-pin chain, curved-attachment chain and plastic-sleeve chain. The attachments accommodate special fixtures or blocks for specific conveyor functions.

Much like rack-and-pinion or belt-and-sprocket sets, the belts in a rigid-belt actuator (such as this RigiBelt from SERAPID) engage pinions. However, the belts are ribbed on one side and molded with studs on the other. As the pinions spin, the belts turn 90° through and interlock. Notice the idle rollers that guide the chain links around the pinions. — Much like rack-and-pinion or belt-and-sprocket sets, the chain-like linkages in a rigid-belt actuator (such as this RigiBelt from SERAPID) engage pinions. However, the belts are ribbed on one side and molded with studs on the other. As the pinions spin, the belts turn 90° through and interlock. Notice the idle rollers that guide the chain links around the pinions.

Accumulating conveyors are one subtype of conveyor chain that suit applications that need more control over product flow, such as packaging or assembly.

Self-lubricating chains excel in harsh environments

These are useful in applications in food and beverage, paper product or wood-processing industries where traditional lubrication presents too much of a contamination or clogging risk.

Chains are also available with specialty coatings for rugged environments. Stainless steel is a good choice in applications exposed to corrosion, but because this material cannot be hardened in the same manner as carbon steel, it doesn’t have the same load carrying capacity. Nickel-plated chains are another alternative, providing some protection for mildly corrosive environments. More after the jump.

Shown here is a mobile chain application, a trencher from Shelton Sportsturf Drainage. Its digging chain runs off the tractor power takeoff; twin augers flanking the chain move dirt away. Called the Shelton CT150, the vehicle uses laser-guided grading to evenly install drainage pipes. Hydraulics control trench depth; a pipe layer lifts out of the ground for easy starts.

Factors that limit chain life: Corrosion, wear, fatigue

If a chain application requires long life without contamination, pick chain with self-lubricating subcomponents. If the roller chain application requires high precision, pick chain with precision roller bearings at each link connection.