At M&M Aerospace Hardware Inc. (Miami), quality counts. The company distributes nuts, bolts, washers, rivets and other hardware to manufacturers. Founded in 1974, it now has more than 300 employees and eight locations in the United States, Canada and Europe.

The company’s customers judge its quality based on the accuracy and speed with which it fills its orders. For example, when counting some 1 million rivets, M&M Aerospace needs to be certain the count is accurate. Previously, the scales used were only 94 percent to 95 percent accurate. But that isn’t nearly accurate enough for a company that provides parts to the aircraft manufacturing industry. Consequently, M&M Aerospace had to sacrifice speed for accuracy. In an effort to obtain a more accurate count, the company was required to reweigh the parts several Arial, which resulted in additional time to fill orders.

To improve the accuracy of its scales and reduce the amount of time needed to pick parts, the company chose Setra Systems Inc. (Boxborough, MA). Setra’s Super II counting scales and weight sensing technology seemed a good fit.

The Super II scale uses variable capacitance technology. Variable capacitance uses a device consisting of two parallel gold-plated electrodes fused onto a ceramic load cell. The electrodes have a minute gap between them. They are wired into an LC oscillating circuit. When a load is supplied to the scale pan, it causes the ceramic beams to bend, changing the gap across the two electrodes, which changes the capacitance in the electronic circuit.

Changes in capacitance result in changes in the frequency of oscillation. As weight is added to the scale, oscillation frequency may vary as much as 2 million cycles per second. A microprocessor in the scale can detect changes as small as one cycle per second, providing the scale with extremely high internal counting resolution. The Super II can measure a weight change of as little as one part per million. And because the concept is simple, there are few moving parts to fail, making the scale extremely reliable.

M&M Aerospace relies on the scales not only when fulfilling an order, but when it orders hardware from its suppliers. When an order arrives, the staff makes a dimensional inspection of the hardware, checking to ensure that all paperwork is in order. The hardware is forwarded to the receiving department, where all parts are counted using Super II scales.

"Everything we do, every order we receive, is counted out by weight so that we know our vendor has sent us the exact count that we ordered," says Terry Bond, vice president of quality.

The results have been dramatic. Since purchasing 86 Super II scales, the company has improved accuracy more than tenfold. By using the scales, the company has been able to count parts at an accuracy level of up to 99.5 percent. Instead of having a count that is off by perhaps 5 percent, M&M Aerospace can now determine a count with an error of fewer than 5 parts for every 1,000 parts counted.

Another important consideration for Bond was speed. Time savings are now realized when parts go out and when they come in. "Actually, by using the scales, we eliminated a couple of steps from the procedure of counting the parts and reduced the time needed to count parts by about 30 percent," says Ray McCormick, director of warehousing.

With the previous system, the company used a multistep process to reduce the percentage of error to an acceptable level. "We would count parts two or three Arial to get the ratio down. Now, on these new scales, all we have to do is weigh a sample, hit ‘count,’ and we get a reading that is already accurate," says Bond. The amount of time that has been saved means that orders can be filled faster and more accurately. This, in turn, has generated increased productivity and improved inventory control.

Currently, the actual count is reconciled with the order manually, but because the scales are compatible with computers, reconciliation will soon be done automatically. "We are in the process of hooking up all of our scales to our computers, so whenever we need to weigh, all you have to do is put the box on the scale, hit "enter" and the computer automatically reads the weight of the box and processes the order," says McCormick.

For more information on scales, call 800-257-3872 or visit