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issue: May 2005 APPLIANCE European Edition

Assembly and Fastening
Assembly at the Speed of Light

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by Douglas Graham, Contributing Editor

New materials, methodologies, and technologies have advanced the pace of assembly and fastening to the speed of light. Many of the latest concepts are grounded in common sense and meet OEM demands for solutions that are appropriate for doing business in a tough economy.

Un montage à la vitesse de la lumière
Les fabricants d'appareils électroménagers peuvent accélérer le processus de montage et de fixation grâce à des matériaux, méthodologies et technologies. Un bon nombre des derniers concepts utilisés coulent de source et répondent à la demande en solutions rentables permettant de faire des affaires malgré une conjoncture économique difficile.

Assemblare alla velocità della luce
I produttori di elettrodomestici stanno velocizzando i processi di assemblaggio e di fissaggio grazie all'ausilio di materiali, metodologie e tecnologie. Molte delle innovazioni più recenti sono basate sul buon senso e soddisfano la domanda di soluzioni a costo contenuto per operare con rigorosa economia.

Montage - blitzschnell
Gerätehersteller erhöhen dank neuer Materialien, Methoden und Technologien das Tempo von Montage und Befestigungsverfahren. Viele der jüngsten Konzepte beruhen im Wesentlichen auf gesundem Menschenverstand und erfüllen die Anforderungen nach kostenwirksamen Lösungen für den Betrieb in einer hart umkämpften Wirtschaftslage.

Appliance assembly and fastening has simultaneously become more and less automated. This development has occurred part and parcel with a deeper trend to de-emphasize automation throughout the global manufacturing sector. Two drivers are pushing this trend—economics and pure practicality. While automated systems often deliver significant ROI over time, they aren’t cheap, and for some manufacturers the price of automation may be too high to justify plant-wide deployment.

Other players in the appliance industry say that in some cases, automation is ruled out because it is costly and sometimes irrelevant to their operations. Automated assembly is used most effectively in large volume manufacturing situations, these OEMs argue, but when smaller numbers are typical, it’s best to do business the old-fashioned way.

“ While the concept of total automation has great appeal in terms of its ability to save money over the long haul, it may not be practical in every manufacturing scenario,” says Buz Reed, vice president of Operations at U-Line Corporation, an appliance maker based in Milwaukee, WI, U.S. “U-Line, for example, is a medium-sized company that produces many models, each in quantities quite a bit more modest than what you get with mega-players like GE and Maytag. Our volume warrants the use of some automation, but only in select applications.”

Some manufacturers say the decision to automate is based in part on the continuing exportation of appliance manufacturing to regions such as Mexico, Central Europe, and especially China, where labor costs are so low compared to what is typical in developed countries that it actually makes better economic sense to pay people to do work increasingly intended for machines. Even as it applies to domestic manufacturing, appliance OEMs are drawn to solutions that offer practicality. According to assembly technology experts, brand-name appliance makers have not gone deaf to technology’s siren call, but many are more interested in the value propositions technical innovations lay on the table.

“ The manufacturing migration to Mexico and China has made automation a less important issue than it was before the migration began,” notes Doug Cote, manager of Sales and Applications Specialty Products Group for BTM Corp., a provider of non-welded mechanical clinching solutions based in Marysville, MI, U.S. “Automation is all about saving labor costs so you need less of it when labor is cheaper.”

Appliance makers are working hard to cut costs, and one of the ways they’re achieving that is by finding alternatives to traditional fastening, Mr. Cote adds. BTM’s Tog-L-Loc product is a screw-less fastening solution employing clinching, a method by which two sheets of metal are interlocked without the use of screw or rivets. OEMs find Tog-L-Loc attractive, Mr. Cote says, because with it they can do away with screws and rivets, and save big time on piece part cost.

A worker assembles a water heater using the SPOT CLINCH® Alligator 0302 AS V4 from ATTEXOR Tools S.A. of Switzerland. The clinching tool’s slender and chamfered jaws permit access to the joining zone, despite the fact that the water heater features a strongly curved profile. According to the company, running self-tapping screws in this situation would be a major hurdle, and spot welding would damage the paint.

Managing the Machine

“Over the course of the past 24 months or so, we’ve seen customers who were vested in full automation increasingly opt for semi-automated solutions,” says Lori Logan, marketing manager, DEPRAG Inc., a supplier specializing in automated assembly equipment with U.S. offices in Lewisville, TX. “This change has occurred in the wake of the global economic downturn. In the hard light of the current economic reality, many manufacturers are no longer willing to sink big bucks into pricey technologies that promise payoff down the road. Rather than roll the dice on significant capital expenditures, many customers are investing in semi-automated solutions incorporating quality control features such as depth, torque, and angle options.”

The notion that total-automation is cheaper in the long run than all alternative manufacturing processes has not held up given the tough economy and the new generation of sophisticated semi-automated equipment, Ms. Logan continues.

This is not to say that there are significantly fewer automated systems in operation in the appliance industry right now than there were a few years ago. Automation has settled into the appliance industry and is here to stay, but it has not penetrated as deeply or aggressively as once anticipated. According to Ms. Logan, roughly 25 percent of assembly and fastening operations are accomplished via semi-automated hand tooling, 50 percent is done manually, and the remaining 25 percent through totally automated solutions.

“Most of the tradeoffs between automated and manual assembly have to do with cost and control of operation,” adds Gordon Tosh, product engineering specialist at W.C. Wood Company, an appliance maker based in Guelph, Ontario, Canada. “With automated assembly, you have more technicians to support, so while the machines do away with operators, they create the need for more techs, and someone has to pay those people. Automation is also an all or nothing proposition. When one machine develops a cough, the whole system gets pneumonia. Automation has the added downside of costing more upfront, but on the plus side, it can save you on time and labor expense when everything works as it should. Automation radically increases production speed as well, and gives you far greater consistency and accuracy.”

The dividends paid by assembly automation, however, compensate for its drawbacks, Mr. Tosh contends. Automation mandates greater accuracy, for example, as all the holes have to be lined up properly just so to make the system go. It also makes the creation of complex parts possible without the need of multiple components. For a cost-cutting appliance producer, this is a huge advantage as it limits the number of assembly operations required to get a new product ready for the sales floor.

“One of the ways that automation saves us money is by taking steps out of the assembly process,” Mr. Tosh says. “Incorporating parts into a single piece allows us to do less assembly, which means that complex parts can be made with less complication. In the old days, the plant assembled freezers from separate pieces. Now it uses an automated process incorporating a big press and bending system, which blends all the components into a single unit. Welding and riveting are cut way back and likewise the labor, material, and utility costs associated with such operations.”

The 752 Series from EFD, Inc. (East Providence, RI, U.S.) is said to be a compact, low-maintenance dispense valve that applies cyanoacrylate adhesives and other assembly fluids on automated production lines. To minimize maintenance, there is no tubing to leak or O-rings to wear out. Instead, the company says a long-life precision diaphragm that is rated for tens of millions of cycles provides long, trouble-free operation. To meet OEM requirements for efficiency and reliability, an adjustable stroke control allows the flow rate to be fine-tuned, while valve open time is regulated with a microprocessor-based VALVEMATE™ controller. Mounted near the valve, the controller is said to simplify system setup and allows valve open time to be adjusted in increments as small as 0.001 seconds.

Practical Automation

“Implementing automation may require significant initial investment in capital, time, and resources as extensive retooling of current processes are often required,” explains Peter C. Thomas, product manager, Assembly Systems, Emhart Teknologies Industrial Division (New Haven, CT, U.S.). “On the other hand, while manual assembly requires little capital investment, you must take into account such factors as the human element (operator skill), quality, ergonomic concerns, environment, and productivity throughput.”

A customer should decide on solutions based on its current assembly methods, Mr. Thomas says. Taking them into account, it should ask itself if the ROI promised by the equipment and associated solutions will justify their cost, and if the answer is yes, how quickly? There are other questions to consider as well: Will the new solution improve productivity? Can quality levels be improved as a result of its deployment? Is a reduction in labor achievable via its use? Can rework and secondary inspections be eliminated? Is the equipment easily maintained or serviced and by whom? Is the equipment adaptable for future production model changeovers?

Bill Dwyre, director of Global Marketing for Ingersoll-Rand Co., adds that there are several key considerations to bear in mind when choosing assembly and fastening equipment. “Product is only one piece of the equation,” he says. “Suppliers must provide solutions which include the evaluation of the ergonomic relationship between the tool, the task, and the user. This will help optimize the process and improve both productivity and end product quality.”

To achieve optimal throughput, most assembly systems contain a mixture of both automated and manual workstations, comments Mark Dinges, linear motion and assembly unit product manager, TS assembly conveyors for Bosch Rexroth Corporation Linear Motion and Assembly Technologies in Buchanan, MI, U.S. “Automated workstations are ideal for quick cycle times and provide a high positioning repeatability for precise assembly,” he explains. “They are also effective if an assembly operation is potentially too dangerous for an operator.”

Depending on the level of assembly complexity, manual workstations may be the optimal solution, Mr. Dinges continues. In order to minimize start-up capital costs, an assembly system can potentially be constructed entirely of manual workstations. As throughput requirements and process complexity may change, manual workstations can be changed-out with an automated or a series of semi-automated workstations. The modular design of non-synchronous assembly conveyors make them ideal for achieving such retrofits.

Enabling auto-feed riveting, the AutoSet™ system from Emhart Teknologies Industrial Division features a one-touch cycle mechanism that frees one hand to hold the application while riveting.

Fastening Evolution in Action

The on-going trend of phasing-out old joining methods with newer and better ones continued through 2004 and will almost certainly achieve greater forward momentum through 2005, says Hans Bergkvist, president and CEO, ATTEXOR Inc. in Springfield, MA, U.S. and ATTEXOR Tools S.A in Switzerland. Self-tapping screws and blind rivets (often called pop-rivets), for example, are becoming common components of mechanical joining processes, even in cases where the price of the fastener and the processes associated with deployment are cost factors.

“Fasterner-less assembly methods such as clinching continue to gain market share over other assembly techniques,” Mr. Bergkvist says. “Clinching offers several advantages above and beyond the fact that the cost of buying, sorting, and feeding screws and rivets are avoided via its use. The method is clean, silent, and with assembly cycle time well below 1 second, exceedingly fast. Furthermore, clinching is both ecologically and environmentally friendly. The process generates no sparks, fumes, or electrically generated fields.”

Clinching will become extremely popular with appliance makers in the near future, Mr. Bergkvist adds. The industry is also likely to adopt more in the way of hybrid assembly, in which various types of adhesives are used in combination with clinching. With this probable development in mind, ATTEXOR is working on several projects with key adhesive makers to develop assembly parameters using clinching and adhesives together.

Leaping Hurdles

When new trends debut in the appliance marketplace, they sometimes create new, but not unsolvable challenges, Mr. Thomas of Emhart Teknologies says. To cite one example, appliance producers increasingly use thinner, lighter metals and materials to reduce cost. The trouble is this also makes the parts more difficult to assemble with traditional mechanical fasteners. This, coupled with the ever-increasing use of pre-painted metals, has led to more advanced fastening methods such as self-piercing riveting (SPR) technology, which eliminates the need to pre-punch holes in advance and later realign them for riveting.

“A corollary development has been the increased use of blind rivets and associated, high-speed installation systems, in particular those which eliminate the handling of individual rivets,” Mr. Thomas explains. “These new technologies include semi- and fully-automated systems and systems in which blind rivets are pre-loaded on a strip.”

Cutting-edge solutions in assembly and fastening allow OEMs to increase productivity and ensure consistent processes yields at higher quality levels, Mr. Thomas continues. Another example of this principal is offered by advanced electric setting tools in which self-piercing rivets incorporate an inline force transducer that measures the force curve from the instant the rivet touches the base material to the completion of the joint formation. This feedback virtually eliminates poorly formed joints. The increase in quality results directly from the elimination of unnecessary rework, scrap, and warranty claims and is accomplished through the use of technology that is designed to monitor the entire process from start to finish.

“To thrive in today’s global economy, appliance OEMs must work harder than ever before,” notes Ms. Logan of DEPRAG Inc. “Assembly and fastening solutions providers help them achieve that by offering practical product that saves time and labor, and vastly enhances efficiency.”

Suppliers mentioned in this article:
Attexor Inc.
Attexor Tools S.A.
Bosch Rexroth Corp.
BTM Corp.
Nordson EFD
Ingersoll-Rand Co.

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