Assembly and Alignment Issues

GA Lynlynch. Simple, concise, to the point and the outline of the complete paper. I suggest a internship at a manufacture of large equipment.

If I read your question correctly, you wish to optimise quality production coming from a complex machine system where the finished item must be aligned at several work stations and a several steps of assembly must be done.

If, again, this is a correct interpretation, then it would be something not attempted in manufacturing facilities.

Simple assembly (placing label, filling, capping, coding and cartoning) is the target of current manufacturing practices. That should be the goal of engineers. Simplify.

We currently run a 137 units per minute, about 58,000 finished at the end of a 10 shift. And we try for simple. I can't imagine but our OEE would be worse than it currenty is.

I am sorry to be so pessamistic, but I wish engineers in my place would focus on simple and reliable instead of a lot of whirrrrring...then a red light....then a crash.

"lots of alignment and assembly to be done"

1. Use as many as 'self aligning' techniques as possible. eg: tapper shanks in drilling m/c.

2. Ensure the perfection. eg: laser tools.

My favoured approach is to design the product so that it aligns itself when it is assembled. Machine to closer tolerances, add dowel pins, include slide fit mortice and tenons into adjoining faces. Also consider combining some of the components into a single machined part. You can't eliminate machining tolerance, but one machining tolerance is better that a build up of three machining tolerances plus an assembly tolerance.

A good design will take into consideration the manufacturing method as well as the component build up. A laser cut end frame will always be more consistent than one assembled from several parts. Eliminate procedures like welding and brazing which add stresses and distort the shape of the parent metal. Even laser cutting will create distortion when applied to thick metal. Use water jetting instead.

Another standard technique more commonly applied to machining, but equally applicable to assembly, is to clamp the work pieces on individual platens (assembly jigs) and then transfer to platens between work stations. The platens have dowel holes that mate precisely with each work station eliminating both set up time and alignment errors This method is generally employed on high value, high volume, items that can justify the cost of the platens. Google pictures of television assembly lines for an example.

All of the above depends on good documentation. Tell the supplier/manufacturer not just what you want but how you want it made/assembled. A design should be far more than just the drawings.