Once a ball bearing product goes into production there’s very little scope to reduce its cost. Faster machines and more automation can only have a small impact. This is because much of the cost – 80% by some estimates – is set by the design. The components and materials used, and the manufacturing tolerances required, determine most of the final cost. That is why good product design processes consider cost along with function.
A simple example of cost considerations for ball bearings is standard versus custom components: it’s always less expensive to use a standard ball bearing. This avoids nonrecurring engineering costs and setup and tooling charges because the design, development and tooling has already been done. It’s also usually a quicker way of obtaining parts than seeking custom-made ball bearings.
The downside is that the catalog items may not be an exact fit or deliver the precise performance called for in the requirements documents. In this case it is up to the design team to weigh the savings and benefits of going with standard rather than custom components.
Ball product function usually steers the designer toward materials with the right blend of hardness, strength, and mass, but this can be a costly route. Consider substituting a less expensive material and add coatings or heat treatment to deliver the surface or performance needed. Conversely, sometimes a stronger but more expensive material lowers overall ball bearing manufacturing costs because so much less is needed or it permits savings elsewhere.
Stainless steel is corrosion-resistant but expensive. A carbon steel may be only slightly inferior in terms of corrosion but a lot less expensive: how about adding a powder coating or plating to help prevent rust in your ball bearings?
Aluminum has a higher strength to weight ratio than steel. Switching to aluminum could save weight while only slightly increasing bulk and at the same time allowing the use of lighter components elsewhere in the assembly.
Tight tolerances are expensive. A rule of thumb is that each additional decimal place on a dimensional tolerance doubles the cost of producing that feature. Reasons for this include using slower manufacturing processes (grinding rather than turning); needing more precise, and hence more expensive machines; additional inspection requirements, and possibly lower yields.
The message here for designers is to consider the tolerances needed very carefully, and to avoid use of overly tight default values. Oftentimes it is possible to configure assemblies to minimize the impact of tolerance stack ups or to add some compliance or adjustment.
Cost is, or should be, as much a part of the ball bearing design requirements as weight, speed, appearance or life. Giving it due consideration upfront permits more comprehensive evaluation of trade-offs and design decisions and results in a product that better meets customer expectations. The alternative, trying to engineer-out costs after design approval, is slow and never yields the same magnitude of savings.
Hartford strives to delight customers with high-precision, high-quality ball bearings, bearing assemblies and precision balls that enhance product performance and customer experiences. Contact us to learn more.
Hartford Technologies, Inc.
1022 Elm Street - Rocky Hill, CT 06067
Tel: 860-571-3602 | Fax: 860-571-3604
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