Carrying the can and doing a lot more besides

There is a famous scene in the 1936 film Modern Times in which Charlie Chaplin plays a worker being driven crazy by monotonous, inhuman work on a conveyor (bit.ly/1qyoNYm). It's a brilliant piece of slapstick comedy. Another sparkling comic performance comes in the 1950s TV series I Love Lucy where American comedienne Lucille Ball struggles to keep pace with an accelerating conveyor belt in a candy factory (bit.ly/1gNDcun). Perhaps in part because of this sort of absurdist monochrome humour, people tend to see conveyors as rather clownish, old-fashioned pieces of equipment. In fact, far from being comical or outdated, conveyors are perfectly adapted to present-day manufacturing needs. Factories that make little or no use of conveyors often find that they can speed and improve materials handling and manufacturing processes by introducing them. But conveyors can do far more than simply move stuff from A to B. Manufacturers are increasingly looking to gain information from their conveyor systems. For example, conveyors can help make production more efficient by: - Counting – items placed on a conveyor can be totted up as they pass a checkpoint. The information can then be fed back into a computerised inventory control system so that total stock in transit is known at all times and specific numbers of items or weights of materials can be routed to the required destinations. - Online weighing – individual items or palletised stock can be suspended on overhead conveyors and weighed in transit and the information recorded. Bulk materials, meanwhile, can be accurately weighed in transit on belt conveyors. - Sortation, accumulation and routing – goods can be identified and steered to the appropriate destination to be assembled, form a consignment, or be dispersed. - Cooling – Sending a hot product (for example, a newly-welded part) around an overhead conveyor system gives it time to cool online. - Workstation feeding – machines and manual workstations can be fed the required items automatically for processing, assembly or inspection, and then returned to circulation via a conveyor. Additional time between stations can be provided by holding stock on conveyor loops or freewheeling roller conveyors until required, or by splitting the procession of workpieces along several parallel tracks. It might also pay to consider creeping conveyors, long recognised as a valuable production aid in vehicle manufacture. Conveyor speed is adjusted to allow time for the manufacturing processes at a workstation to be completed. - Improving quality – goods can be inspected in transit on conveyors. To allow inspection, the mass of product might be divided into a number of slow, narrow conveyors through an area provided with high quality illumination where staff can monitor quality. - Boosting health and safety performance – legislation rightly obliges employers to prevent their employees being exposed to risk of injury through manual handling. There are many ways to tackle this: break up the task, break up the load, redesign the task, or introduce equipment to help. But, in many cases, companies are looking at more radical solutions. Health and safety laws extend to the ergonomics of the workstation as well as the amount of twisting, handling, and stretching required. Overhead conveyors, for example, can solve many manual handling problems. The flexibility of height and the ability to rotate products easily with overhead technology lets you create conveying systems geared specifically to workers' ergonomic needs. - Painting or irradiation – Paint spraying and drying can be handled on a batch basis, for example, with lower energy consumption, better use of paint materials, and reduced solvent emissions. Components travel on hooks on an overhead conveyor for the electrostatic application of powder paints. Another common treatment is for the conveyor to pass through a screened tunnel for the product to be irradiated with ultraviolet energy, as in the polymerisation of instant drying inks used for printing on non-absorbent surfaces such as metals and plastics. Basic conveyor principles can also be adapted to suit the requirements of special applications such as moving products into and out of clean rooms where airlocks are applied. In this application, the product might, for example, free wheel on rollers until the second airlock door opens and then move forward. Gary Bale of LB Foster Materials Handling (www.conveyors.co.uk) believes more conveyors are being used in factories now than ever before for several good reasons:"Companies are looking for safer manual handling and conveyors give you that. They also give you improved productivity and quality. All this comes at a cost, but it's worth it; typically, I'd say you'd be looking at a return on investment within two years." But beware. All conveyors, of whatever type and for whichever application, are potentially dangerous. By their nature they are not usually enclosed by guards and conveyors that operate under remote control carry extra risks. Consequently, both an audible and visual warning are needed before start-up. Capacity can also be a safety issue. This can be addressed with load cells which can be installed to trip the drive of an overhead conveyor when an excess weight is detected. To ensure that the drive can't be energised while inspection, maintenance or repair is being carried out, it pays to fit a switch or padlock to lock out the motor drive switch. On large conveyor installations, the use of permit to work procedures is advisable if work is to be performed out of sight of the main control position. Emergency stop push buttons or pull wires must be installed at high risk positions and staff training in the use of conveyors and the safety measures pertaining to them is, of course, essential. The HSE offers a wealth of advice on conveyor safety – http://bit.ly/1jHYEDD The three main conveyor types Floor conveyors. These systems, typically belt-driven, occupy permanent floorspace. They attract dirt and debris, and they may restrict access to the manufacturing process. They are, however, relatively cheap and easy to install, and it's hard to imagine an overhead system that can compete purely on cost. Meanwhile, towline conveyors – towing a bogey carrying a product along on- or in-floor tracks – are typically used in the assembly process. Overhead conveyors. Chain or cable driven for conveying objects, tote baskets, or buckets, these systems can have both powered and unpowered sections, loops, sidings, T-junctions and merging junctions, etc. They free up valuable floorspace, although they can be expensive to install and they can result contamination as debris falls onto the products hanging below. Nonetheless, the technology is well established and proven, particularly in the automotive sector, so you don't have to make a leap of faith to consider specifying it. Roller conveyors. Gravity or powered, these may have freewheeling sections for accumulating items, or heavy duty rollers for pallets and heavy loads Cutting overheads... overhead LB Foster Materials Handling has supplied an overhead conveyor system for Congleton-based Investment Castings. Designed to transport ceramic coated wax moulds during the drying process, the conveyor has enabled Investment Castings to double its production of precision castings. Paul Clarkson, co-director of Investment Castings, says: "UK manufacturing is coming out of recession at last and customers are returning who we haven't heard from for the last three years. This increased demand highlighted the fact that we didn't have sufficient capacity to process as many moulds as we needed. As a consequence, we were getting bottlenecks in production. To overcome this problem we decided to invest in a second overhead conveyor that would enable us to process more moulds." When Investment Castings acquired its first conveyor in the late 1990s, it carried out the necessary research into LB Foster and visited its facilities in Leicester. "This time," explains Clarkson, "we just ordered an identical conveyor from the company as we knew it would not only be fit for purpose and simple to operate, but it would also be entirely reliable." The new conveyor, situated inside a temperature-controlled room, is used to dry out the ceramic-coated wax moulds, transporting them in a continuous loop around three large central fans. There are 26 rotating jig locations on the conveyor and each jig can hold two runners. Each runner can support one large mould or numerous small moulds. It takes two days to process the moulds, with four ceramic coats applied to them on the first day and four further layers on day two. Drying takes place after each coat is applied. After a long overnight dry on the conveyor, the wax can be removed from the mould. The ceramic shell is then fired and filled with molten metal to create the precision casting.