Signature analysis holds key to precise mechanical assembly

June 7, 2001
Timing-belt tensioning and planetary gearheads that maintain out-of-box backlash levels for life are just some of the topics covered in this mechanical reference guide.

An electromechanical assembly press (EMAP) installs bushings in light-truck differentials at Eaton Corp. EMAP systems from Promess Inc. come in nine different sizes up to 22,000-lb force. Systems include the press ram, servomotor and amplifier, PC-based hardware with PLC control interface, Window-based control and monitoring software, and an integrated load cell and preamplifier.

EMAPs (electromechanical assembly presses) from Promess Inc., Brighton, Mich., use a technology called signature analysis to precisely monitor and control assembly. An encoder-equipped servomotor drives a ball-screw ram to which a variety of sensors can attach.

The EMAP simultaneously measures both the force and displacement during a duty cycle then compares this data to a known good operation, something hydraulic-based presses can't do. Finished assemblies with curves that don't match are flagged for further inspection. Setting tolerance limits in this way identifies out-of-spec products before they leave the factory.

Recently, assembly system builder Owen Machine & Tool, Jackson, Mich., installed EMAP equipment at an Eaton Corp. facility. The Eaton plant uses an EMAP to install two bushings in nonsynchronous, locking differentials for light trucks. The bushings are a key part of a mechanism that controls torque transfer from the slipping wheel to the one with traction. "The bushings must be positioned and fit precisely," Burtka notes. "Too loose or tight and the locking feature doesn't work, resulting in unhappy customers and warranty claims."

The electromechanical press is part of what's considered a lean assembly process meaning components are installed with manual presses that can be brought on or offline as needed. Despite the apparent simplicity, all stations are equipped with in-process gaging and inspection. Every pallet has a radio-frequency ID tag for process monitoring. The final step is to simulate on-road conditions.

"The EMAP system quantifies the accumulative impact of all tolerance stack-ups in parts as they relate to individual assembly operations," says Burtka. "It's a much better way to find defective end products than simply measuring individual parts and hoping they work properly when assembled."

Sponsored Recommendations

A closer look at modern design considerations for food and beverage

April 9, 2024
With new and changing safety and hygiene regulations at top of mind, its easy to understand how other crucial aspects of machine design can get pushed aside. Our whitepaper explores...

Condition Monitoring for Energy and Utilities Assets

April 9, 2024
Condition monitoring is an essential element of asset management in the energy and utilities industry. The American oil and gas, water and wastewater, and electrical grid sectors...

Strategizing for sustainable success in material handling and packaging

April 9, 2024
Download our visual factory brochure to explore how, together, we can fully optimize your industrial operations for ongoing success in material handling and packaging. As your...

Fueling the Future of Commercial EV Charging Infrastructure

April 9, 2024
Miguel Gudino, an Associate Application Engineer at RS, addresses various EV charging challenges and opportunities, ranging from charging station design strategies to the advanced...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!