How It Works – Assembly & Innovation

Today’s Machining World Archive: January 2006, Vol. 2, Issue 01

Making value-added a way of life

This plastic cap and metal screw will be ultrasonically welded together for use in computers; the machine can assemble about 40 units per minute.

Innovation at Alpha Grainger Manufacturing, Inc., a Franklin, MA, screw machine house, isn’t just about servo controls, automatic assembly and fancy machine-vision systems. All those technologies and more show up around the plant. But company president Jake Grainger has found that just about anything can be fair game for improvement.

Thinking outside the box

Take boxes, for instance. Filled with parts, they can be too heavy for an operator to lift easily. They can spill in handling. They can break in transit.

When Grainger noticed the problems, he set out to improve the situation. The result? A custom-designed shipping box featuring a sturdy box-in-box design lined with a plastic bag. The box is sized to make sure it won’t weigh too much when loaded with parts. Die-cut slots in the flaps make it easier to lift and less likely to be dropped. When the box is closed and sealed for shipping, the flaps overlap fully, making the box stronger.

In the plant, boxes, bins and buckets of parts ride on custom-made carts designed to keep containers at a convenient height for handling.

After an employee was injured from lifting a 90-pound five-gallon bucket of parts, Grainger changed to smaller buckets. The buckets are color-keyed by department. With smaller boxes, buckets and bins, no one in the plant has to lift more than 30 pounds, says Grainger, and he can’t remember the last time there was a back injury.

The custom boxes undoubtedly cost more, and so do the carts. But in the long run, Grainger says it reduces costs by preventing injuries and boosts productivity by making the work easier.

Making it in Massachusetts

Michael Bourget, Production Supervisor, demonstrates the multiple functions of a Grainger-designed machine in Secondary Processing, where parts are loaded, transferred, milled, keyed and measured.

Successful operation of a manufacturing business in the notoriously expensive state of Massachusetts presents challenges that the company meets by continually improving productivity.

A self-professed “tinkerer,” Grainger has educated himself in disciplines such as mechanics, electronics, acoustics and control systems. “Manufacturing is a continuing process of solving problems all day long,” he says. “Recognize [that] you have some problems. Don’t just fix it every time it breaks. Fix it so it never breaks.”

His idea of fun is taking apart a new Davenport screw machine and retrofitting it with servo systems run by the latest electronics and modifying it to make it run faster and better. He built his first servo-controlled machine in the mid-1980s and continues to explore new ways of making the equipment more flexible, efficient and dependable.

“Where competition sets the pricing, being more productive means making more money,” says Grainger. He attributes Alpha Grainger’s success to a spirit of innovation that flourishes throughout the company, along with a homegrown can-do attitude. To foster creativity and innovation, Alpha Grainger gives the individual department heads authority to buy the equipment and supplies they need to explore and evaluate new ideas. Some ideas don’t work out, Grainger acknowledges, but a lot of them do.

The other aspect of the profitability equation is increasing revenue. In addition to fabricating parts, the company also offers “value-added” processes, such as assembly and 100 percent inspection. Staff at the company, including Jake Grainger and his brother Gary, vice president, has developed the expertise needed to build automated assembly and measurement systems in-house. To support these and other projects, the company has invested in labs, and equipment such as wire electric discharge machining (EDM) units.

“We see assembly as an extension of doing secondary operations,” says Jake Grainger. The company started offering assembly in the 1980s – simple processes, such as putting snap rings and a washer on a part or assembling a lock washer onto an unthreaded screw and then rolling the threads.

Kitting: a simple form of assembly

Some customers are willing to pay to have parts kitted in plastic bags. Alpha Grainger developed an automatic kitting machine that consists of four vibratory bowls, each fitted with an escapement mechanism to feed parts one at a time. The operator programs the machine’s controller for the specific count of each part; two screws, two nuts, four washers and two lock washers, for example. Inductive proximity (“prox”) sensors count each part as it drops to make sure the correct number is included. Below the bowls, an automatic bagger opens the plastic bag to receive the parts, waits for the parts to drop in, heat seals the bag and releases it to a box below.

Jake Grainger oversees an inspection machine. Small automotive parts are mechanically aligned and fed through both mechanical and video inspection stations; a diverter mechanism separates good parts from faulty parts.

Capping screws for computers: assembly and inspection

A large computer company requires plastic caps to be ultrasonically welded on screws and the screw threads to be 100-percent tested. Alpha Grainger’s assembly/inspection machine feeds the screws and plastic caps into an assembly station, ultrasonically welds the parts together, then feeds the assembled screw to an inspection station where a thread gage rotates onto the screw threads the required number of revolutions. Parts with bad threads go into scrap. This machine also monitors the ultrasonic assembly step, and “remembers” which screws had out-of-spec welds, so they can also be diverted into scrap.

Secondary processes with automated measurement

A switch bushing requires secondary processes and also needs to be 100 percent inspected for critical dimensions. Alpha Grainger developed a secondary processing machine where an operator loads the parts into a chute, where a gripper then places them in an indexing wheel. After passing through drilling and stamping stations, the part is inspected for thread, outside diameter (OD) and other dimensions. Finally, the parts are dropped into a chute, where a diverter directs good parts into a shipping container and bad parts into a scrap container. This machine was designed to handle a number of similar parts of different diameters.

Automated 100-percent inspection for an automotive part

Jake Grainger explains that this machine, which was built and custom programmed for the specifi cations of this product, won them the contract.

Some customers, especially in high-volume, high-reliability industries like automotive, require that critical parts have zero defects.

Alpha Grainger gained a contract to supply an automotive part after the existing supplier claimed it was impossible to inspect one of the critical features on a part. Alpha Grainger figured out how to automatically inspect this feature and won the contract.

The parts are about half an inch in diameter and about an inch long, with a conical taper on one end, a circumferential groove on the other, and a through hole. After machining, they are heat-treated and plated. The parts are then 100 percent inspected. If a part is out of tolerance on any of several dimensions, it can cause a field failure that can be very expensive for the auto manufacturer. As a result, Alpha Grainger’s customer is willing to pay for 100-percent inspection. This justified developing an automated inspection system dedicated to this type of part.

In a vibratory bowl, the parts are correctly oriented. They pass through an opening that checks for oversize OD, through inspection stations that use go/no-go pin gages to inspect for inside diameter (ID), and finally proceed to a machine vision station, where the system measures nine critical dimensions.

Good parts fall into a shipping box; bad parts are diverted to scrap. The machine vision system can inspect up to 4,000 parts per hour.

Improvements everywhere

Innovation at Alpha Grainger is not limited to making parts. During the 1980s, Gary Grainger bought an Apple II computer. He wondered what a computer might be good for and set about teaching himself. Under his leadership, Alpha Grainger’s information technology (IT) department has developed programs to monitor location of raw material, work-in-process and finished parts inventory, as well as job status and machine maintenance schedules. The company’s ISO procedures reside on the computer system. The computer automatically sends customers order acknowledgements by fax or e-mail, according to their preference. And it prints the shipping labels for boxes of finished product.

All programming is done in-house, so it is tailor-made for the way Alpha Grainger does business. Gary Grainger tells about the new “imaging project” that will make prints, certifications and records for heat-treating and plating available online. In the past, anyone who needed these documents had to go to the files and physically make a copy. The new system allows staff to view or print a certification or other document at any of the company’s 80 computer workstations.

Improving productivity involves more than solving technical problems. In order to reduce the noise level in the plant, Jake Grainger took inexpensive fiberglass panels, encased them in Mylar to protect them from oil and hung them from the ceiling where they absorb the sound that would normally be reflected.

On the factory floor, every screw machine is fitted with a cutting-oil cooler and a custom lubrication system, and most have electronic controls, all designed and built in-house. Exhaust fans and ductwork remove oil mist at every machine.

Michael Bourget, production supervisor, keeps an eye on things as automotive parts fall from the hopper above, into the vibratory bowl which aligns them before sending them down through mechanical and video-scanning inspection stations.

Ventilation and noise suppression are important considerations in the plant set-up at Alpha Grainger. Fiber glass panels enclosed in mylar hang from the ceiling.

Jake Grainger carefully watches where the money goes. Sometimes inefficiencies show up in surprising places. He determined that it was a waste of money for the machine operators to sharpen tools. “[Now] our machine operators never sharpen any tools,” he says. “Other companies would think it was a crime.

[But if you take] a seven- or eight-dollar drill and sharpen it, it becomes a $30 drill.” With the operator’s time, incorrect sharpening and possible lost production, the dollars add up.

Jake Grainger looks at every day as a new opportunity to find more ways to make things better. “I feel I am so lucky to be in a situation where I can express my creativity,” he says. And while he’s enjoying himself, he’s “assembled” a more profitable business.

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