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Squeaky Chairs Need Grease or Better Tolerance Analysis
Free Webcast on Tolerance Analysis
Recorded Webinars
Year-End Trade Up Promotion
Squeaky Chairs Need Grease or Better Tolerance Analysis
By Karl Luce, Luce Point Technologies, LLC
Many moons ago, I worked for a firm that bought out another firm. Many moons before that, I worked for an engineering department that was bought out by another firm. (Perhaps you can relate?) One thing I have taken away from these experiences is that chaos usually ensues. Along with that chaos is opportunity to scam better tools, better computers, maybe even better office equipment?
I thought I had struck it rich when I inherited a plush office chair from a buyout. Hey, it had rollers which would allow me to glide from one cubicle wall to the other. Granted, that was only eight feet but progress is progress. I could now glide between piles of paper without having to pick up the chair. Woo-hoo!
There was downside though. Any rocking of the chair induced an irritating squeak. It also rocked in a jerky motion that required me to sit still with morning coffee in hand. Otherwise, stains appeared on my collared shirt. It could take many minutes to adjust the height via the handle below the cushion; the effort to move it was so much that I would turn the chair upside down to perform adjustments. Then, once set, a few days later it would fall back into the lowest possible setting. What is wrong with this chair?
Poor product performance translates into unhappy customers. What does a manufacturing organization do to ensure reliable product performance and retain happy customers? The most basic design activity that they can perform is Tolerance Analysis. It is the set of activities, the up-front design planning and coordination between many parties (suppliers & customers), that ensure manufactured physical parts fit and work together the way they were meant to. Knowing that dimensional variation is the enemy and leads to customer dissatisfaction, world-class manufacturers perform Tolerance Analysis before designs are frozen, before any assemblies are put together.
The benefits are many:
- Eliminate “no-build” scenarios (“We can’t put these parts together!)
- Decrease Sloppy or Jerky Product Motions (“Feels like good quality.”)
- Reduce Product Squeak & Rattle (“Why is this so noisy?”)
- Adjust Product Operating Efforts (“Not too loose or too tight but just right.”)
- Lessen Warranty Claims (“I want my money back!”)
- Limit Safety Recall Campaigns (“The safety lock did not latch and I was thrown out of my seat!”)
- Shorten Product Development Cycles (“We launched this product before our competition.”)
Past efforts to perform Tolerance Analysis, such as Worst Case Analysis and Root Sum Squares, have relied on straightforward mathematical constructs to determine dimensional tolerances. They work well enough for simpler assemblies but may lead to overly conservative tolerance ranges within complex assemblies. Associated with the overly conservative answers are greater costs to maintain variation within those unnecessarily tighter tolerances. However, with ample computing power at our fingertips, it makes more sense to utilize Monte Carlo Analysis within the spreadsheet environment and arrive at a result that finds a balance between tolerances, cost and customer satisfaction. It can simulate thousands of assembly builds in a matter of seconds and determine the probability of interferences or other measures of customer satisfaction.
Tolerance Analysis Package
I have put together a package that documents the important role Monte Carlo Analysis (MCA) provides for Tolerance Analysis. Using the example of an overrunning one-way clutch, the paper and associated MS Excel Workbook walks the reader through:
- Identifying assembly outputs (related to customer satisfaction) and their Specification Limits.
- Relating part dimensional tolerances to expected normal probability distributions.
- Performing MCA using ModelRisk on a Tolerance Analysis model.
- Using MCA results to guide future design decisions.
- Optimizing design decisions to meet multiple output requirements.
* In order to run the example model properly, please download the latest version of ModelRisk here
I truly hope this package provides the aspiring design engineer the insight and courage to perform MCA on their own assemblies. For the engineering or production manager, the decision to utilize MCA can be based on cost savings from loosening unnecessarily tight tolerances. Either way, the money and time spent up front to design and predict performance will pay dividends above and beyond cost of customer dissatisfaction.
More on Karl Luce
- For specific questions on tolerance analysis using Monte Carlo techniques and Six Sigma please contact Karl Luce.
- Karl's website can be visited here.
Free Webcast: Tolerance Analysis - January 21, 2013
Want to learn more about Tolerance Analysis? Karl Luce will give a webinar on this topic on January 21, 2013. Subscribe below and mark the date in your calendar.
| Title | Lecturer | Date | Time | Subscribe |
| Tolerance Analysis Using Monte Carlo Techniques | Karl Luce | Jan. 21, 2013 | 11AM EST / 4PM UTC |  |
Free Recorded Webinar
The webinars we have provided over the last months are now available in an online video format. To view the webinars of your choice, please visit this page. Below you will find a list of available recorded webinars:
- Introduction to ModelRisk Standard
- Introduction to ModelRisk Professional (1)
- Introduction to ModelRisk Professional (2)
- Stochastic Optimization
- Modeling Extremes
- Risk Modeling for Basel II
- An Introduction to the PK/PD Module
- Correlation in Risk Modeling
- Linking ModelRisk to Databases
- Splicing Distributions
Year-End Trade Up Promotion (50% Off) & Year-End Budget Purchases
Still thinking about trading up from your existing risk analysis Microsoft Excel add-in to ModelRisk? This is a reminder that the promotion ends on 12/31/12. That’s only a couple of weeks away! Curious if you qualify? Take a look at this link to see if your current and similarly priced software is listed at the independent comparison list.
Also, for those of you with funds available from your 2012 budget and are wanting to invest in ModelRisk, this is a friendly reminder to get your order in before the year’s end. Investing in ModelRisk now will be a great addition to your company’s software tool-kit as you begin forecasting and risk planning for 2013!
Send your request for a quote to sales@vosesoftware.com or contact either our U.S. office at (303) 768-8669 or our Belgium office at +32 (0)9 330 34 82
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