ToleranceAnalysis Excel

If you're tackling a DIY project that requires you to drill through metal, how can you know if you have the best tools for the job? Even if it may seem like a tough material to work with, you can easily drill through metal using a regular hand drill. Keep reading for everything you need to know and with a little patience, you'll be able to safely drill metal for any project!

Tolerancestacks

The location of features is typically the most important characteristic of features in linear tolerance stackups (TS), which is why position and profile tolerance are more commonly included in TS than form tolerances. This is because TS are done to find a minimum or maximum distance and in the majority of cases the form or shape of a feature has little to no effect on the distance being studied.

Tolerance stack calculation

In order to perform the stack-up analysis shown here all tolerance styles must be converted to equal-bilateral form. The figure below shows how this is done.

Before drilling metal, choose the right kind of bit. For softer metals, like aluminum, a high-speed steel bit will work. For steel or other hard metals, use carbide, cobalt, or titanium. Put on a pair of work gloves and safety glasses, then clamp down the piece of metal to hold it steady while you drill. Draw an X on the metal where you want to drill, then make a dent on the mark with a hammer and center punch. Put a coin-sized amount of cutting oil on the spot to help lubricate and cool the drill bit. Hold the drill perpendicular to the metal and squeeze the trigger lightly while applying pressure to help push the bit through the metal. If the metal starts to glow or get too hot, take a break and add more cutting oil. Once you pierce the metal, switch the drill to reverse and carefully pull the bit out. Smooth the edges of the hole with a deburring tool when you’re done. Did this summary help you?YesNo

Stack upanalysis

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A sample of a Worse-case report and sketch is shown below. Note how assembly shift due to floating fastener variation is calculated (two entries) and the importance of how the dimension-chain direction affect the summation of the stack. Fixed fastener variation would only require one entry line in the spreadsheet.

Tolerance Analysis is the only way to determine the allowable variation between the features of a part or between part sizes in an assembly and whether parts will satisfy their dimensional objectives. The analysis is iterative in nature and it could be done from the Top-Down (letting the assembly requirements determine the part tolerances) or the Bottom-Up (part tolerance determine assembly goal). The information gained leads to better understanding of the machine or device in consideration.

A sample of a Statistical report and sketch is shown below. Note that the Root-sum-square (RSS) of the tolerance is used to determine the max. and min. size of the gap. The Worse-case calculation was also included as a way of comparison. As you can see, it shows a possible 3.7mm interference upon assembly.

It is important to note that these calculations apply only to parts and assemblies functioning at 25° C. Thermal expansion or shrinkage must be considered when the device is expected to endure extreme temperatures.

In Case One the perpendicularity tolerance applied to datum feature B allows portions of the Datum Feature to tilt and/or have form error relative to datum B, which is perfectly perpendicular to Datum A. Therefore the tolerance analyst may choose to include the perpendicularity tolerance in the tolerance stack-up. The Perpendicularity tolerance only allows the distance between datum feature B and the groove to decrease, so it must be accompanied by a negative zone shift. The perpendicularity tolerance is added as an equal-bilateral tolerance of ±0.25, with a Zone Shift of 0.25, which is half the perpendicularity tolerance value. The zone shift is indicated by placing the 0.25 value in the -Dir column on the same line as ±Tol. column. Case two is very self explanatory.

The report can be formatted to return the worst-case or statistical tolerance variation. Worse-case determines the absolute maximum variation possible for a selected distance gap. Statistical determine the probable or likely maximum variation possible for a selected dimension. A simple rule of thump to determine which format to use is that as the number of tolerances in the stack increases, the benefits and validity of using a statistical analysis increases.

This article was co-authored by Christopher Thomas and by wikiHow staff writer, Hunter Rising. Christopher Thomas is a Metallurgist based in Birmingham, Alabama. With 16 years of experience working for Commercial Metals Company, Christopher specializes in designing modern infrastructure, metal recycling, fabrication, performance steel, and construction services. His company is responsible for creating high-end structures, from the AT&T Stadium in Dallas to the Pentagon. Christopher holds a BS in Metallurgical Engineering from the University of Alabama. There are 8 references cited in this article, which can be found at the bottom of the page. This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources. This article has been viewed 306,069 times.