Like most components today, ball screws have numerous manufacturers from around the world claiming to provide savings and/or increased performance. Merely believing unproven manufacturers and using their product comes with unacceptable risk to your brand reputation, so either the due diligence must be done in sourcing new manufacturers, or the potential benefits will go unrealized.
From my recent experience sourcing new ball screw manufacturers, here are some key points that designers should be keenly aware of:
In creating a manufacturers list using Global Spec, selecting the product "Ball Screws" and selecting "Company Type = Manufacturer" provides a listing of 111 companies. Upon further investigation of the companies, fewer than 30 were actually manufacturers of ball screws… reason being that selecting Manufacturing and Ball Screws includes those that offer ball screws and are classified as a manufacturer (whether a manufacturer of ball screws and/or anything else).
In order to ensure multiple sources, I was looking at DIN standard nuts. While the DIN standard controls the envelope and mounting dimensions, and I expected some variance in the load rating due to differences in ball conformity, manufacturing, and materials, load ratings varied by almost 2x for the same-size DIN standard nut.
Upon obtaining quotes from manufacturers that meet basic qualification criteria (legal US sales representation, ISO registration, and minimum factory warrantee), price points varied by almost 5x. Some major manufacturers quoted their non-standard nut at much more competitive prices.
Much more information about ball screws is available, including a listing of manufacturers, in a detailed research report.
Greg Lyon holds a BSME from Northeastern University, is a licensed professional engineer in New York, and is the inventor on 17 US/International patents. His professional career consists of more than 30 years in engineering, including the past 11 as president of his own engineering and R&D company.
Naperlou, thank you for your comments. The issue of screening new suppliers has certainly become more complex and risky than ever before, with new manufacturers from around the world claiming quality products are reduced costs. As you say, no one wants to, or has the time to wade through hundreds of thousands of (maybe) qualified suppliers. In our work, we came across many from China with incredibly low prices, but no US sales representation, no ISO, and no warrantee. Certainly not of interest for a serious user. Once you have this list of potential suppliers, as you said, they need to be tested, as catalog specs can be marketing/copied and/or theoretical numbers. The testing then needs to weed out the non-performers, but can be time and cost intensive, and sometimes awfully hard to justify. A conundrum!
There is a new company, Industrial Product Reports, which provides a Consumer Reports type service for industrial products (www.industrialproductreports.com). Thoughts?
"Free" (to the user) directories like Global Spec are notorious for including all kinds of products one is not looking for, even when an "advanced" search engine is provided. I've encountered this there and elsewhere, including trade show directories, when looking for companies I write about, or might write about. Sometimes the problem is in the design of the category choices vendors must select, sometimes it's because the vendors check off too many boxes in those categories. Overall, I think it's because the directory is not paying people to QC the data.
Gregory, you have run into a real problem with search engines on the Internet. This is a problem of favoring speed over accuracy. I guess that for free search that is what you get. Oh, wait a minute, it's not free. Search is paid for by advertising.
The problem you point out is an important issue in using search results. I wonder if most people will remember a time, not long ago, when someone would mention the number of results of a search as a serious quantity. Then, perhaps, they noticed that almost any simple query returned hundreds of thousands of results. If one looked at it, one would find that the results after the first couple of pages were not relevant.
Another point in your article is very important. You need to make sure that the vendor is legitimate. You really need to go at least one step further. You need to test the items. I have seen situations where manufacturers got items from their normal reseller, but from a different supplier, and the items turned out to have problems. They ended up either loosing the manufacturer lots of money, or putting them out of business. A reputable manufacturer is really a must.
From design feasibility, to development, to production, having the right information to make good decisions can ultimately keep a product from failing validation. The key is highly focused information that doesn’t come from conventional, statistics-based tests but from accelerated stress testing.
There’s a good chance that a few of the things mentioned here won't fully come to fruition in 2015 but rather much later down the line. However, as Malcolm X once said, "The future belongs to those who prepare for it today."
Pressure vessels are part of common equipment utilized in plants to store liquids and gases under high pressure. It is certain that pressurized fluids will develop stresses in the vessel, which when exceeds failure limits, will lead to hazardous incidents and fatalities.
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