October 12, 2022
Once you have an idea what your device will look like, the urge to start designing is strong. Before you start calculating gear ratings, however, there are important things to do. Trust me on this — if you skip ahead in the process, you will end up revisiting various aspects. Before you start actually designing your device, make sure all the “stakeholders” are in agreement on what the end result has to look like. Mission creep is very real; while you are off juggling tooth counts, face widths, center distances, and all the other “engineering’ things, your customer, sales force, and manufacturing partners are forming their own expectations. Unless you freeze the “rules of engagement” early, revisions will be required. Better to think things through and get a written agreement before any chips are made. A good way to accomplish this is to prepare a product specification and get everyone to approve it. So what does a “product specification” include? Think of it as a check list of “must haves.” Start with the request for quotation and make a list of the customer requirements. This is when you work out expectations on service factor, ratio matching, input speed, duty cycle, life expectancy, inspection covers, lifting provisions, lubrication systems, cooling provisions, venting, special paint, and many other features. If it is not in the product specification, no one should be surprised if it is not in the final product. Having a checklist should not limit your effort to build a “world-class” device; it allows plenty of opportunity to make each component the “best” it can be while still fitting into the cost envelope your manufacturing system likes. Critical to customer satisfaction is compliance with interface requirements; put reference drawings and third-party standards in the specification and make sure that everyone understands them. [At this point, I am sorely reminded of having to take apart, re-machine, and re-assemble 44 gearboxes because the customer’s reference drawing was reverse-angle projection instead of the third-angle project used in the United States. If that doesn’t make sense to you, you are at risk of having to learn the hard way as well.] That product specification also needs to include any safety requirements applicable to the device. Are you supplying coupling guards or is someone else? What will the device weigh? Where is the center of gravity? Will it be shipped with oil in it? Are the lifting provisions to include capacity for things the customer or others will mount to it? Don’t ruin a great project by after-the-fact, unpleasant surprises. Even shipping — often the least-considered yet equally important part of a project — can cause extreme heartburn. For example, who is responsible for packaging the device so it does not get damaged in transit? If it has to be shipped in pieces, who re-assembles it at the job site? Having a template for your product specifications will insure that lessons learned get transferred from one project to another. Just make sure you know what is in that “boiler plate”!