Small shop, big decision

Welding robots aren't just for big shops anymore.

Traditionally, robotic welders have been used by large shops specializing in high-volume production. But competitive pressures, a lack of skilled labor, quality assurance, and a number of cost factors have made these systems attractive to smaller shops. What they are seeing are automated welding cells with tooling that can handle fast-paced changeovers, easy programming, and other technological advances. Factor in lower costs, and suddenly robots are no longer tools for only high-volume shops.

Smaller shops are probably one reason business is booming for robotics suppliers. During the 1990s, for instance, the number of new arc-welding robots installed in the U.S. and Canada grew 12% each year. In 1999, orders for spot-welding robots rose 102% in 1998. And even with the economy cooling off, robotics companies still had a good year in 1999, says Donald A. Vincent, executive vice president of the Robotics Industry Association (RIA). According to RIA, the industry shipped more robots in 2000 than ever before, beating the 1999 record by 5%. And RIA estimates there are over 110,000 robots currently working in the U.S.

These robots are more affordable than a decade ago with a complete automated welding cell starting in the $60,000 range. While the drop in cost is attractive, it's the labor market that has pushed a lot of smaller shops toward automation. In many regions, there are not enough young welders coming into the industry to replace those retiring. As a result, shops are finding it hard, if not impossible, to fill sudden large orders.

Some firms have started recruitment and training efforts, which can be a costly gamble. These companies spend considerable time and money to produce a skilled welder, with no guarantee the person won't leave for the shop down the street after his training is finished.

Robots over-come these problems. Training is not an issue, because someone can learn to run an automated welding cell in just minutes. In one case, a small California manufacturer of creep-ers for auto mechanics faced a labor shortage. In an effort to keep up with demand, the shop bought a $65,000 robotic-welding system. Within 10 days, the system was in place, and after some simple tooling, basic programming, and a little training, the robot proved its worth. One operator produced what once took four skilled welders.

The factors involved
Some small firms look at their labor rate and quickly conclude it's cheaper not to automate. However, it's not simply salaries that should be considered. What should be weighed is the fully burdened labor rate, which includes the cost of the building, taxes, utilities, transportation, and more. When all those issues are considered, some shops find employees cost them $80 to $90 per hour rather than $35 to $40.

There is also a reliability factor. Even the best employ-ees sometimes get sick. The worst employees may not show up at all, and most work-ers are somewhere in-between. Robots, on the other hand, never ask to leave early.

Another advantage of robots is increased productivity. Often, a robot can be two to five times as fast as other welding methods, thereby providing a return on investment in six months or less. In fact, developments in electrode technology, welding torches, and vision systems let robots weld at speeds fast enough to reduce overall costs, even for companies that produce a limited number of different parts. A rule of thumb is that robots should provide a minimum 100% increase in productivity.

It's also important that small shop owners know it's no longer necessary to dedicate a robot to one particular task. Several programs can be stored in a robot's memory, allowing it to weld small batches of several different parts. All that is needed is an operator to change out the tooling nests and tell the robot which program to use. The result is an increased number of parts finished and a lower overall cost per part.

In addition, programming, once an excuse for many shops not to use robots, is now a simple matter. Interactive screens let work-ers, even those who must over-come language barriers, learn to program a robot in a couple days.

One benefit often overlooked is that robots take up less shop space than an employee. In some cases, robots prevent a shop from having to buy or rent extra space.

Automated welding cells also save shops money on supplies. A skilled welder builds a margin of safety into the welds he makes — often using more filler material than needed and making the bead longer than necessary. A robot is exact; it will lay down only the amount of filler material needed. The result is less splatter and wasted filler. One automotive stamping company justified the cost of two robotic-welding systems solely on the cost saved on finish grinding the completed welds. Robots also allow shops to buy weld wire in larger bulks, reduce inspection time and costs, and reduce burnthrough and distortion on thin metals.

The marketplace has increasingly demanded accountability from suppliers, and this is another area where automation helps a small shop. Monitoring software can be installed on a robot that records and reports weld data on a real-time basis. Other programs allow for auto recovery should there be a robot fault on the shop floor. Also available is password protection that can provide a summary of any changes made in the welding process during production runs. All these packages let small shops maintain high quality regardless of personnel.

Not all things to all shops
While a robot may sound like the answer to a shop's prayers, not all applications lend themselves to automation. Positioning, clamping, and tight access to a welding joint may mean automation isn't feasible. If the parts are not designed properly, or the joints are not well prepared and presented to the robot, there will be problems.

The parts being welded also must have a high repeatability. Variation often hampers automation. Consequently, clamping and fixturing must be precise. While a skilled welder can work past an ill-designed fixture, varying trim lines, and inconsistent dimensions, a robot's ability to do the same is limited.

That said, a shop shouldn't dismiss automation simply because an application is complex. Some of the latest fixtures can hold up to 20 parts, meaning a shop can tackle integral design and difficult geometries.

Making a choice
Once a plant decides to investigate robotic welding cells, it should seek a reputable vendor that will work with it to determine the appropriate system accessories, the welding system to be used, safety devices, layout, fixturing, training requirements, cell design, power sources, controllers, wirefeed packages and maintenance requirements.