Chain-based conveyor systems offer flexible layouts and material flow designs. They're used globally with handling and automation technology to transport products around warehouses and manufacturing facilities. As part of the conveyor itself, they move along guide rails either in straight lines or complex curves, pulling or carrying conveyed goods along their paths in a wide range of applications.

More specifically, plastic conveyor chains are used in the automotive and electronics industries as well as with furniture, food, beverage, and packaging industries and in the production and conveying of cosmetic, pharmaceutical, and chemical products.

Plastic versus metal

Plastic conveyor chains are up to 40% lighter weight than their steel counterparts, which means that they can be driven by smaller, more energy-efficient motors. This significantly reduces energy consumption and lowers operating costs. What's more, plastic conveyor chains can be designed with surface textures specific to the product being conveyed.

Using plastic also cuts noise emission levels by up to 80% compared to metal chains, making it easier to adhere to occupational noise exposure regulations. In addition, while metal chains must be regularly cleaned and lubricated, chains made of wear-resistant synthetic materials do not require lubrication and are completely maintenance-free. Using integrated injection-molded chain links also reduces assembly time, resulting in significant cost savings.

Conveyed goods determine chain choice

Plastic chains can be tailored to the specific requirements of various conveyed goods, and integrated functional parts are made by injection molding to further broaden plastic-chain design options.

Case in point: For smaller goods of discrete dimensions and widths to about 300 mm, flat top or multiflex chains are the best choice, as they come in widths from 40 to 300 mm. Multiflex chains feature universal joints, which transmit the tensile forces symmetrically to the chain link in curved conveying sections and thereby guarantee a longer chain service life. With the simpler joints of flat top chains, in contrast, track curvature is achieved through play between pins and chain links.

For conveyed goods wider than 300 mm, and for unsorted product streams, modular belts are the preferred choice. These are constructed from separate, modular plastic chain links that can be assembled to any width. Due to their design with many finger-like links, modular belts feature exceptional strength, allowing goods weighing up to 100 kg each to be conveyed. Special versions may be used for loads weighing as much as 1 ton.

Special grip top coatings increase friction with the conveyed goods, so that inclines can be included in the conveying path without risking product slippage. The opposite effect — a reduction of friction between the belt and conveyed goods — is achieved by incorporating small rollers in the chain surface. (This reduces the chain's force on backed-up products to almost zero.) For smaller goods, chains with 100% gap-free conveying surfaces are available, while perforated or slotted chains allow liquids to drain through the chain.

Materials for all uses

Besides chain geometry, plastic conveyor chain material also influences performance. Because the chain geometry is usually defined by both the injection molding tools used and established market standards, tailoring the chain to specific application requirements is possible only through careful material selection. Note: Some functional dimensions, such as chain link pitch, must remain constant for all materials.

Because plastic types shrink differently during manufacture, there are some limits on material choice. However, despite this limitation, it's possible to produce chains from different materials and to make certain modifications for various applications. As a default material for plastic chains, polyacetals are effective because they can be modified to meet specific requirements. Combining excellent friction and wear characteristics with a high dimensional stability and good strength and rigidity, they meet all the material requirements for plastic conveyor chains. Other high-performance thermosetting plastics are often unsuitable due to high cost.

Following are a few examples of the versatile nature of polyacetals and where they find use:

  • For applications in the electronics industry, in which the build-up of electrical charges must be prevented, chains made from plastic modified with conductive carbon black are suitable. This material has an exceptionally low surface resistance of 1 × 105 Ω.

  • Polyacetals can also be modified with aramide fibers to suit other applications. These increase the material's wear resistance so greatly that conveyor chains made from this material can be used in extremely abrasive environments, such as the glass and ceramics industries.

  • To lower friction values or decrease a conveyor's noise emission levels, polyacetals can be modified with special friction-reducing additives. Note: All modifications impact the material's mechanical properties, so must be applied with care. Additives can also significantly increase material cost.

For more information, contact iwis drive systems LLC at (317) 821-3539 or visit iwisusa.com.