Assembly in Action: Torque Tool Builder Locks Calibration
In final assembly, the tools are calibrated by adjusting a screw on each side of the T-handle. A small amount of cyanoacrylate adhesive is then applied to each screw to hold it in position. However, this simple task became a major issue when a new customer ordered a large batch of wrenches.
Because the customer was going to use the torque tools to change live electrical modules, the shafts and handles were encased in an insulating plastic coating. The plastic coating would help avoid injuries and short circuits, explains Bob D’Aiello, Seekonk Manufacturing’s quality assurance manager.
After the tools were assembled and dip-coated, two small holes were drilled in the cured coating to permit access to the calibration screws. The tools could not be calibrated prior to coating because the heat of the process could change the settings. After adjusting the screws, the assembler applied cyanoacrylate by inserting the tip of a squeeze bottle through the hole.
On Seekonk’s all-metal torque tools, the calibration screws are completely visible to the assemblers. However, on the coated tools, the access holes limit the ability to see how much adhesive is applied.
Hundreds of the coated wrenches had been in use for several months. But then the customer called with a problem. One of the tools had failed to slip at the correct point and nearly stripped a bolt. When D’Aiello took the tool apart, he saw that too much cyanoacrylate had been applied to one of the calibration screws. The excess had wicked down into the tool’s internal mechanism and prevented it from releasing at the correct point.
With the balance of the contract hinging on Seekonk’s corrective action, D’Aiello contacted EFD Inc. (East Providence, RI) and purchased the 1500XL-CA, a microprocessor-controlled fluid dispenser. The 1500XL-CA is a compact, tabletop unit that operates on compressed air and electricity and dispenses cyanoacrylate in accurate, repeatable amounts. The adhesive is contained in a disposable syringe reservoir connected to the dispenser console by lightweight, flexible tubing. The user holds the syringe like a pen, places the tip in position, and presses an electric foot pedal to apply a preset amount of adhesive.
The 1500XL-CA features a teach function. This makes it simple to determine the correct amount of cyanoacrylate to use for a specific application. Deposit size can be fine-tuned by increasing or decreasing the length of the dispensing cycle in 0.1-, 0.01- or 0.001-second increments. Once the optimal cycle time for a particular application is known, it can be entered the next time that job is run.
The dispenser’s consistent cyanoacrylate deposits and ease of operation have removed the variability from Seekonk’s dispensing process. Unlike the squeeze bottles, where the amount of cyanoacrylate being applied depends on the skill and judgment of the individual, the EFD dispenser ensures that the same amount is applied every time.
"After extensive testing of the 1500XL-CA, we knew we could be 99.9 percent sure the tools would not fail in the field. When we invited the customer to our plant and had their engineers try the dispenser for themselves, they were convinced, too," says D’Aiello.
"Not one tool has locked up since we switched from the squeeze bottles to the EFD dispenser," he concludes. "It helped us hold on to a key account and preserve a 60-year reputation."
For more information on dispensers, call 800-556-3484 or visit www.efd-inc.com.