Not too long ago, critical high-volume automotive components like engine blocks, cylinder heads and transmission housings were machined on highly dedicated transfer lines and assembled with equally dedicated systems. Introducing a new engine or transmission required a multimillion-dollar investment.
Then came “flexibility” and “lean” and “cells” and “agile” to change everything. Except, as the French say, “plus ça change…,” meaning the more things change, the more they stay the same and we find ourselves in a familiar rut.
Let’s say you’re developing a new product, a cylinder head for example. Once the design is complete, it will be up to a manufacturing engineering team to figure out how to produce it. They will build a prototype using machining centers, robots and an ad-hoc collection of other highly-flexible components to do a production and assembly proof of concept.
Then, once all the bugs are worked out, they will design and order a system to produce the product. Of course, that system won’t look anything like the proof-of-concept prototyping system and it will be built to produce a given number of components annually based on sales projections. If the product is a success, the standard response is to order a duplicate system, which may not be fully utilized.
This is essentially the way we’ve been doing production and assembly for the last 100 years or so. “Plus ça change,” indeed.
While all this is going on, that proof-of-concept system has probably been disassembled and repurposed many times. Chances are that at least some of the components weren’t up to production standards and in that form, it probably wasn’t a good candidate solution.
But what if those components were up to production standards, and furthermore, what if they were both modular and fully reconfigurable? In that case, it’s quite possible that the prototype system could be moved directly onto the production floor.
The system can be easily replicated to accommodate any increased production requirements using standard, off-the-shelf components. Reduced production requirements would simply mean putting the unneeded components back in stock, awaiting another need.
One of the 20-kN Electro Mechanical Assembly Presses (EMAP) my company builds weighs roughly 400 lbs (180 kg).
That’s exactly what is required to achieve the kind of standardized, reusable and reconfigurable system building block we are discussing. So, let’s see what can be done.
The EMAP is a servo-driven mechanical press with a steel housing and heavy-duty bearings, motor and ballscrew. It’s built like a tank to make sure it performs well beyond customer expectations. That’s why it’s so heavy.
Many of those features, however, are not needed on a press intended for use as a robot end effector. Here’s what our engineers suggested to eliminate as much weight as possible from the press:
- Add “flats” to the outer housing, to eliminate steel and reduce overall weight.
- Eliminate unnecessary features like the mounting flange, connectors, and cables that aren’t necessary for a robotic press.
- Use a smaller motor and gearbox.
The result? A press capable of up to 50 kN and 350-mm stroke that weighs less than 150 kg, well within the capability of a large robot.
Controlling reaction force is another challenge with a robot mounted press. It is, however, easily overcome by simply building a hard stop into the fixture and letting the press float up until it comes in contact. At that point, the hard stop controls the force rather than the robot arm.
At this point, it’s feasible to have a fully instrumented, programmable, servo-controlled press as a robot end effector. That means it’s possible to keep standardized, reconfigurable and retoolable assembly workstations that cover all common assembly operations “in-stock” to be configured as ad-hoc assembly systems as, where and when needed.