Top Gear9 January 2020
About 30,000 separate parts come together to make a single car. A single delay on the assembly line can be disastrous. Julian Champkin looks at lifting requirements in the automotive industry.
Vehicle production involves cutting and pressing steel, welding, assembling huge numbers of parts that range in size and weight and material from tiny screws via glass light bulbs and fabric seat covers to truck chassis whose weight is measured in tonnes. Shapes—body shells, engine blocks—can be awkward; alignments must be perfect; and above all, the production line is everything.
“As is well known, continuity in production is one of the main priorities of the vehicle industry,” says Oguzhan Gülerci, export specialist of Turkish hoist-makers CMAK. “Any interruption in production would bring huge problems and costs and is unacceptable. And we know that the cranes and hoists are the one of key components of the production line.”
Reliability is therefore an absolute; and systems that monitor the hoists to be sure that they will remain reliable is something that CMAK and others offer to those in the automotive industry.
“In light of that need, CMAK’s HoistSense+ electronic control unit is the most well-adapted technology which we present to our vehicle-making clients, as well as to other user industries,” says Gülerci. “HoistSense+ is a crane monitoring system, and also a supervising system, with high-technology sensors and Industry 4.0 integration.
“The system operates as a crane supervisor, through its integrated sensors, and gives information about the status of the crane such as actual load, safe working period, and service time. It checks temperatures, brake linings and inverters, and if it finds something wrong it alerts the user and allows the necessary action to be taken. Thus, the stops caused by crane break down are minimised.”
Another key factor in the automotive industry is speed of construction. Minutes saved or lost on each vehicle add up to large sums and can make the difference between profit and loss. Here too the lifting apparatus can play its part. “There is always a race against time in the vehicle industry,” says Gülerci. “For that reason the ‘Ultra Speed Function’ of the HoistSense+ gives an advantage to the user.” An example of the system in use is at a plant making military trailers—see the case study below.
Fred Tangelder, automotive field representative for US lifting specialists Gorbel, has 20 years of experience in the sector. “The loads that are lifted in automotive construction are not huge,” he says. “I have seen loads of as little as 30lb (13kg) that need lifting equipment installed to handle them. At the other end of the spectrum might be 1,500 or 2,000lb (700– 900kg) loads; but more typical is probably in the 100–1,000lb (45–450kg) range. That will cover almost everything from a flywheel on an engine to a pressed bodyshell that is being moved to its chassis.”
Columbus McKinnon covers a similar load range for automotive industry applications. “We provide a full range of components, such as body-decking hoists used to pick up vehicle components along the assembly line, wire rope hoists, variable frequency controls and so on. They are used on cranes ranging from 1/8t to 2t small jib cranes and workstation cranes in individual work cells, all the way up to 30t and 40t overhead cranes in the stamping plants,” says Ed Butte, director of global strategy and product development.
“What is key in the automotive industry, though, is quantity and frequency,” says Gorbel’s Tangelder. “The plant may be producing 800 units on each shift. That can translate to a repeated movement every 30 seconds; and for a human operator to perform that number of repeated movements, at that frequency, for that length of time is fatiguing. So they will want assistance machinery to help with the lifting and positioning; and the technology for that becomes interesting.
“Some options are electric chain hoists, air balancers, or cylinder-driven lifting machines. The application, and that allimportant frequency rate of repetitions, might not absolutely determine the technology but it may often restrict the choice of technology that is used. For example, if an electric hoist is required to perform 800 lifts and deposits a shift, an electric chain hoist might not be the best option for that because it is slower, and the relay control will be subject to considerable wear and tear. A better choice might be an air balancer, or an H5-rated servo-driven lift.” (The H5 classification is for duty cycles approaching continuous operation with up to 600 starts per hour.)
“Higher loads, for example 200lb or 300lb (90–140kg) lifts, such as of a fullydressed engine or a transmission, will still be doing 800 cycles a shift because every sub-unit on the line must keep up with the rate of car production. Electric chain hoists are possible for that application; but to lift the larger loads you might have a large air balancer, or two units, dual air balancers, a left-side and a right-side, working in unison to pick up that weight.
“The choices come down to considerations like that, taking into account what gives the best fit to the application.
“How the lifting method is chosen in each application will also depend on what each company and its engineers want. They may have personal preferences; they may have favourite vendors and favourite brands, depending on how well products have performed in the past. Mostly it comes down to the individual engineer and his outlook, and how the sales person presents the products. “So you could have a plant that is deciding to harmonise on one technology, for example electric chain hoists, or air hoists, from a preferred vendor; its machinery and its choices will evolve over time in the light of experience.
“The other big thing in the automotive industry is down time. Even 60 seconds can matter. If a hoist or crane continually breaks down, or if it is very hard to repair when it does fail because it is complex or there are no parts quickly available to fix it, the company will try to stay away from it in future.
“So makers gravitate to the technology and products that have been up and running for longest. That truly is a huge driver in the automotive industry.
“Those considerations apply to OEMs, the big people like Honda and Toyota. They apply just as much to Tier 1 suppliers, that is, makers further down the line who supply at least one component for each car, say makers of steering modules or gas tanks. They too have to keep up that same hefty production rate, to keep up with the vehicle production rate. So if you are making a complicated component such as an engine, your cycle time is pretty close to the vehicle maker’s.”
Perhaps unexpected is that, in the US at least and to an extent in Europe as well, complete digital control is not at the forefront in automotive construction. “Digital sophistication, perhaps surprisingly, I have not seen a lot of at all,” says Tangelder. Two factors may contribute to this: “Automotive has traditionally been a labour-intensive industry, and people tend to stick with what has worked well in the past.
“And many applications dictate a handson operation at the point of delivery. Taking components out of dunnage is an example. When you are unloading parts they will be densely packed together so that they are optimised for the number of parts on a pallet. That means they may be too closely packed for the gripper mechanism of a hoist easily to take hold of them. That presents a problem for automation; but it is no problem for a human operator who has an assisting technology on his lifting machine.
“Similarly, when bringing a component onto the assembly line it may have to be deposited in exactly the right orientation onto the component that is already on the line. Boltholes must exactly align, locating pins must engage, and so on. Several surfaces must line up exactly and simultaneously. The human eye and hand may still be the most cost-effective solution to that, as long as help is given to the human muscles involved. So such lifting and positioning applications tend to be as automated as possible, but with the operator still driving it by hand.
“And he or she is still doing 800 handson operations per shift; which means that ergonomics is therefore a big player in design of your lifting apparatus. For maximum productivity you try to filter out as much human error as possible, so lines and machines are very highly engineered to reduce or eliminate those human errors that could be introduced. That is the goal of any company making the tools for automotive production.
“Such toolmakers would like to go to total automation, but it is cost-prohibitive. The density of parts, as we have seen, is one factor. The density of operators is another. Substitute a robot arm for a production-line operator and that robot has to be fenced in, for safety; and that takes up space along the line. Indeed it can easily multiply the length it needs on the line three-fold, or even by a factor of five. A line five times longer than it needs to be is not cost-efficient. So manufacturers still use human operators, because it is sensible for them to do so.
“There are also some very subtle considerations. A robot, either wheeled or a robotic hoist, can go from A to B to deposit a load very easily; but it will go exactly to B. It may be required to put down its load exactly onto another part, to which it will be joined—but the required consistency in the whole system is not there. The second part might not be in exactly the right place for the robot to deposit it. It may be a few millimetres to the left or right. There is enough flexibility on a conveyor belt or transport mechanism for uncertainties of plus of minus six inches. So humans still retain all those types of material handling tasks, because of the infinite variability that is required in setting down each part.
“Components must travel along similar paths each time, but not along identical paths. So control of the hoist is a hands-on affair, using lift-assist rather than complete automation. Flexibility is needed; and the human operator supplies it. So digital controls do not play well in these scenarios.” Thus it is that technologies such as CMAK’s HoistSense+, mentioned above, are so well suited to the automotive industry. Other companies also offers products with that design philosophy—technology that helps but does not control. Gorbel here proudly offers its G-Force technology. “One feature of G-Force is that it offers an infinitely variable speed,” says Tangelder. “Chain hoists have two horizontal speeds, fast and slow; and as you approach the delivery point the slow speed may still be too fast. The operator needs more finesse than that. He or she may have to pull back a little and approach again. You are fitting surfaces together, and angles and locating pins and bolt-holes must be meshing at the same time; so you need a variable speed on your hoist: Go fast for the initial part of the journey, slow right down to line it up before trying to make the final landing and the marriage. So G-Force lets you get it right the first time.”
And the slow-down on approach can be set automatically: “I can set a limit of slowdown for, say, two inches before delivery. There is automatically shifts to a lower speed. That gives you an accurate approach. It works very well in automotive: they love that feature.”
G-force offers, he says, upper and lower limits on heights. “Those set a defined work envelope. That stops you wasting time lifting too high so that you have to send more time coming down again; and similarly, stops you going too low. It works to make the lifting more efficient.”
Columbus McKinnon, too, offer this marriage of automation with the human touch. “We provide semi-automated crane control systems that are widely used in the automotive industry,” says Butte. “These solutions are suited for a wide range of automotive processes, and for companies that manufacture vehicles as well as for Tier I suppliers.” And their uses are manifold: “Some specific applications include dipping and coating, assembly, painting, storage and retrieval, among others.
“Our cranes are suited for example to dispatch automotive stamping dies from the stamping press to storage areas and from storage areas to stamping presses in a safe and efficient manner.”
Safety features include configurable restricted areas or ‘no-fly zones’, where normal operation is either not allowed or limited. “We provide systems that can designate areas where cranes are programmed to stop or slow down. There are remote control bellybox transmitters for ‘go/no-go” situations.’ Another unique system, ideal for the automotive industry adds Butte, is the Pro-Path Automated Workstation Crane. It is available in semi and fully automated configurations depending on application needs.
“In its semi-automated configuration, also known as auto dispatch, ProPath allows automated movement, while also using human assistance for precise actions,” he says. “Movement is initiated via Magnetek-brand radio remote controls or pendant pushbutton stations. Impulse variable frequency drives power the bridge, trolley, and hoist motions. As the crane travels to designated locations, operators are free to work on other critical tasks rather than manually guiding the crane and its load.
“Intelligence built into the fully automated ProPath configuration manages the flow of materials throughout the manufacturing process, requiring limited human interaction beyond initial setup. Accurate, repeatable processes reduce idle time, provide consistent operation and improve cycle times. This higher level of automation provides continuous analytics and diagnostics to keep operators informed of the status of the system at all times. System feedback allows for planned maintenance to minimise downtime. Variable frequency drives monitor parameters such as hook height, load status, and speed throughout the process. Most importantly, manufacturing processes become more efficient.
“Air Chain Hoists, such as the CM ShopAir, are also popular in automotive applications where the hoists are in constant operation,” he says. “Air hoists provide high speed and continuous duty cycle so there is no concern with overheating. Recently, VFDcontrolled electric chain hoists, such as the Lodestar VS, have become more popular. These hoists have easily programmable position limits with smooth acceleration and deceleration, which reduces the time it takes to position the hook. And VFD control allows for faster lifting speeds when the hook is not loaded greatly improving the efficiency.”
We have seen above that some manufacturers favour air hoists, some electrical. As technology improves, Columbus McKinnon are finding in some cases a shift: “As some assembly plants try to move away from airoperated material handling equipment, we have supplied hoisting equipment with variable frequency controls that allow for very high operating speeds and duty cycles,” says Butte. “A variable speed driven hoist does not experience a reduction in operating speed as the load is increased, which is a common issue with air driven hoists. And air hoists can produce airborne mists. Eliminating that improves manufacturing quality, particularly in finish assembly areas.
“Hoist synchronisation, for applications where multiple hoists are used together to lift or move a load, sway control, which also improves the accuracy of load placement, and anti-shock technology, which automatically stabilises loads by detecting and minimising rapid increases in motor torque, add to efficiency and productivity; Microspeed allows operator to make precise, slow movements.”
In the automotive industry, it seems, hoist are gives operators ever more assistance; but all down the line the human being is still in control.