HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Comments
View Comments: Oldest First|Newest First|Threaded View
Dave Palmer
User Rank
Platinum
The case of the breaking brakes
Dave Palmer   6/24/2011 3:03:42 PM
NO RATINGS
Powder metal parts can cut costs, but (as with any material or process) it's important that there be a good match between the application and the material.  The award-winning parts seem to be good examples of this.

Unfortunately, I've also seen examples of parts which never should have been powder metal.  For example, I was once involved in a failure analysis for a mechanical brake actuator which consisted of a hub with a long shaft.  Since the compaction direction was along the axis of the shaft, and the length of the shaft was more than twice the diameter of the hub, it was difficult to achieve a high density in the shaft.  The shaft was subjected to torsion and bending loads.  Depending on the exact size and location of porosity, fatigue cracks would initiate at the base of the shaft.  With repeated actuations, the shaft would snap off, rendering the brake inoperable.

Making the part out of powder metal may have saved money in the short term, but this could have been a very expensive problem if anyone had been injured or any property had been damaged (fortunately, this never happened).  As it was, a significant sum of money needed to be spent on this issue.

Of course, there are PM techniques which could have been used to solve this problem.  For instance, double press / double sinter would have made it possible to achieve a higher density.  Powder forging would have allowed an even higher density.  But once the part was already in production, either of these options would have required significant new tooling expenditures.  Ultimately, after examining a number of options, it was found that it was cheaper to machine this part from an inexpensive forging.

There are many applications for which PM is a great option.  However, design engineers need to make sure that it is a good fit for the application.  PM suppliers should also be careful to bring up any potential areas of concern during the design review process, so that any potential issues can be resolved before the part goes into production.



Partner Zone
Latest Analysis
Tesla Motors might be planning to boost the driving range of its two-seat Roadster to 400 miles.
RFID offers visibility into the plant. What inventory is being consumed? What stuff is being built? What's done and out the door?
More and more robots are becoming more autonomous all the time. Now Lockheed Martin has completed a demo mission with two completely autonomous robotic vehicles performing resupply, reconnaissance, surveillance, and target acquisition.
Take a look at the top 20 US undergraduate engineering programs. Then tell us -- did your school make the cut?
Producing high-quality end-production metal parts with additive manufacturing for applications like aerospace and medical requires very tightly controlled processes and materials. New standards and guidelines for machines and processes, materials, and printed parts are underway from bodies such as ASTM International.
More:Blogs|News
Design News Webinar Series
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
7/17/2014 11:00 a.m. California / 2:00 p.m. New York
6/25/2014 11:00 a.m. California / 2:00 p.m. New York
5/13/2014 10:00 a.m. California / 1:00 p.m. New York / 6:00 p.m. London
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Sep 8 - 12, Get Ready for the New Internet: IPv6
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: September 30 - October 2
Sponsored by Altera
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service