To sum up, Tolerance stackup analysis is a very important part of product design. It also helps in reducing part cost. Various tolerance stackup analysis methods are available.

Mathematically tolerance zone is equal to the multiple of required process capability and total standard deviation for the assembly. Lower the value of process capability, narrow will be the tolerance zone and higher will be the rejection.

Tungsten steelcomposition percentage

In the above example, the total stacked disk height/thickness will vary from 66.258 mm to 67.74 mm. We suggest you also use this calculator to calculate total disk height using worst case tolerance analysis.

Compressive strength refers to a material’s ability to withstand being squeezed together (compressed). To test compressive strength, an external force places pressure upon a material, tracking to what degree the material can resist size reduction. A widely accepted test for compressive strength is Mohs Hardness Test. The test relies on a scale that rates minerals from 1-10, or softest-hardest.

Statistical tolerance analysis is based on the Bell curve and normal distribution. For example, when a thousand disks of the same size are manufactured. Disk thickness will vary from upper limit to lower limit. But all disks will not measure the same because their thickness will be distributed.

For a good understanding of tolerance stack up. We suggest you first read this article on What are Limit, Fits, and Tolerance?

One question is troubling me. “Standard deviation is calculated by considering manufacturing process is 3 sigma capable.” -> Std deviation = total tolerance/ (2×3). This one I understand.

Worst Case tolerance stackup analysis method utilizes simple arithmetic (addition and subtraction) operations to calculate optimized tolerances. In this method, all dimensions are assumed at the extreme limit. For low production volumes, worst case tolerance analysis is recommended.

Similar to worst case tolerance analysis, the first step in RSS tolerance stackup analysis is to create the dimensional chain. It is used to determine the direction of tolerance. In the above example, all dimensions are in a positive direction.

Tungsten is one of the strongest natural metals (142,000 psi). However, tungsten is brittle and known to shatter. On the Mohs scale of hardness, tungsten is rated at a 9. Using the different types of strength outlined above, it’s easy to see why choosing the single strongest metal is difficult. For instance, let’s look at tungsten vs titanium.

I do not have much knowledge of the sampling theory approach. But my understanding is we can use it since it is based on statics only.

Nice writeup. Please note that there is a typo for the 3 sigma area under the curve of the normal distribution bell curve. It should read 99.72% rather than 95.72%. Regards.

Production of closely mating parts without tolerances is economically unfeasible. Tight tolerances can result in an increased rejection rate and manufacturing cost. Whereas loose tolerances can affect product function. Therefore it is always recommended to define optimized tolerances. Part tolerance optimization increases the part tolerance band. It also helps in reducing part manufacturing costs.

According to the worst case tolerance stack up analysis disk stack height can vary from 65.5 mm to 68.5 mm. Whereas according to the RSS method disk height can vary from 66.2584 mm to 67.74162 mm.

Tungsten Steelprice

Since a metal’s strength depends on multiple factors, there isn’t a simple answer to the question, “what is the strongest metal on earth?” Instead, there are several metals that are known to be among the strongest.

Statistical tolerance Analysis does not focus on the extreme dimensional limits. Because variation in manufactured part dimensions is not linear. Each dimension has a unique distribution based on the part manufacturing process, machines, and other parameters.

Yield strength refers to a material’s ability to withstand permanent deformation or bending. It’s a way of testing the elastic limit of a given material. Usually determined via a bend test where two ends of a beam or bar are gripped, and stress is applied. The intent is to discover how much stress it requires to exceed the material’s yield point, or the point at which the material will not return to its original shape upon removal of the stress.

In this example, maximum and minimum disk stack-up height is calculated by adding nominal dimensions with upper and lower tolerance respectively.

Hi, I like using your stack up calculator spread sheet. Can you share the password so I can name my project? Thanks Sean

Various tolerance stack up analysis methods are used to calculate optimized tolerance values. Each method has its own advantages, limitation, and application. Out of these Worst Case and Statistical Tolerance Analysis methods are more popular. Let’s discuss these methods in detail.

While there is no definitive "strongest metal" that ranks highest across all categories, selecting the right metal for your application requires a deep understanding of their unique strength properties.

What istungsten steelused for

You mentioned in your calculation the direction of the stack. if you have a 6th step, lets say an etching step, that removed a portion of the last disk, would you include the statistical tolerance calculation of that 6th subtractive step into the same way you did for the RSS of the first 5? or would you RSS the 5 additive steps and then get a tolerance analysis done, followed by an RSS of the 5 steps with the subtractive step?

Tool steel is a type of carbon alloy used for tool manufacturing. Its hardness, abrasion resistance, and ability to retain shape at high temperatures make it one of the strongest metals on the market. The ultimate tensile strength of A2 steel can reach upwards of 1860 MPa.

Inconel is a group of nickel-based superalloys known for their ability to withstand extremely high temperatures. When looking at Inconel's tensile strength, it can reach up to 103-160 ksi (compared to stainless steel’s score of 73.2 ksi). Due to its temperature-resistant qualities, this alloy is considered one of the strongest on earth.

Tolerance stackup analysis is used to calculate optimized part tolerances. It can be done manually or using stackup analysis software.

Sir, Can you help in calculate pin diameter and their distance tolerance for manufacturing tolerance for gauge design ? Assuming three holes are diameter 10+/- 0.1,diameter 15+/- 0.2 and diameter 25+/-.1 these holes distance is 120+/-1,100+/-0.5 and 80+/-1.5 respectively. Please share with formula to my Email

At Mead Metals, we're passionate about helping our customers choose optimal metal solutions. Our comprehensive "Complete Guide to Metal Products" covers key considerations like:

Can you provide a presentation or resources to guide in creating tol stack analysis stack diagrams, to include any assembly of 3 or more parts with a fixed fastener screw rectangular pattern? Simple disc stackup is clear but I am not clear how to handle more difficult aforementioned multipart ‘fixed fastener’ assy stack up.

Your spreadsheet is incorrect. For – 1.05 +0/-.01, the two values that are calculated are -1.06 and -1.05. The two values should be -1.05 and -1.04.

In your bell curve normal distribution curve there is an error – for 6 sigma, instead of 99.72% you have marked 95.72%, and as a newbie I spent 20 minutes to re-affirm that… just wanted to let you know. Thanks for this article and calculator, it’s really helpful!

If I calculate the total deviation (not std deviation) I get 1.4832… that is +- 0.74162 (the same as in your calculation). My formula that I used: (0,5+0,5)^2+(0,1+0,1)^2 .. (0,4+0,4)^2)^-0,5 ~ 1.48324.

Tungsten steelvstungstencarbide

In RSS tolerance band is not reduced, you actually allow some rejection compared to worst case tolerance. And the advantage of this allowable rejection can be given to supplier in term of tolerance.

Tensile strength refers to a material’s ability to resist tension. In other words, it looks at the amount of force required to stretch or pull something apart. A material with low tensile strength would pull apart more quickly than a material with high tensile strength.

Tungsten steelvs stainlesssteel

Total nominal disk thickness is calculated similarly to done during worst case tolerance stackup analysis by adding the nominal thickness of all disks. Therefore

Because otherwise, if the there is only one and the same process capability value to be used after it’s chosen – there is no need the include it to the calculation. Or am I missing something?

In RSS, the tolerace band is reduced. How it will help the supplier to produce parts. reduced tolerance band is the constraint for supplier, right?

Standard deviation is calculated by considering manufacturing process is 3σ capable. Mathematically standard deviation is equal to two times of process capability because the process is distributed on both sides. Therefore standard deviation for 3σ process is given by:

It’s easy to see that trying to make a direct comparison is a bit like comparing apples to oranges. Whether you look at chromium vs inconel, titanium vs steel, or tungsten vs stainless steel. It just doesn’t quite make sense.

Informative log Clears my all confusions of tolarrlence stack up analysis… Language used is very easy to understand and satal.

Why do we need to determine the process capability index in the first place? Is the answer that first we need to determine the manufacturing process capability (e.g. 3 sigma) – and second we need to determine the process capability for the assembly “event” (that can differ from 3 sigma)?

I don’t understand the RSS scaling of the total tolerance band by 1/(2×3) to get the total standard deviation. If we assume the errors are uniform distributed – the standard deviation should = tolerance band/sqrt(12) = tolerance band/3.46. This is close to the factor of 3 used – but I don’t see where the additional factor of 2 comes in….

Chromium is a hard and brittle transition metal with a steel-gray color. This metal is rated an 8.5 on the Moh’s Hardness Test, making it one of the hardest metals on earth. The only metals above chromium on this chart are boron (9.5) and diamond (10).

Let’s consider an example of five different size disks with different tolerances stacked on one another. We will calculate the overall maximum and minimum total stacked disk height using Worst Case Tolerance Stackup Analysis method.

The first step in doing tolerance stackup analysis is to create the dimensional chain. It is used to determine the direction of tolerance. In the above example, all dimensions are in a positive direction.

In this example maximum and minimum disk stackup height is calculated by adding nominal dimension with upper and lower tolerance respectively considering required process capability value is 3σ.

Titanium metal is an elemental earth metal with an extremely high melting pot. It has a notably high strength-to-weight ratio, making it an ideal metal for applications where weight is minimized, but strength must be maximized.

Tolerance Stackup analysis is a design tool used to analyse and optimize product design for assembly. It is used to calculate the cumulative effects of part tolerances in an assembly. Therefore tolerance stackup analysis ensures smooth part assembly on the production floor. In this article, we will discuss the worst case and RSS methods to solve tolerance stack up problems.

Impact strength refers to a material’s ability to withstand a blow without fracturing or shattering. In other words, it’s a method for determining the limit of how much energy a material can absorb via impact.

How do you calculate if an element in the stack-up has unbalanced tolerance? For example X +0.5/-0.1 or X +1/-0? Do you shift the “nominal” and then balance the tolerance, or is there a more accurate way to calculate the final tolerance stackup?

Tungsten and steelproperties

As mentioned above, tungsten is the strongest of any natural metal (142,000 psi). But in terms of impact strength, tungsten is weak — it’s a brittle metal known to shatter on impact. On the other hand, Titanium has a tensile strength of 63,000 psi.

Tungsten steelcomposition

I’ve been told if there is a sequence of just 2 dimensions then RSS is not required. I can’t find where this rule originates. Can you confirm?

When looking at titanium’s density, with a pound-for-pound comparison, it beats tungsten. Regarding compression strength, titanium scores much lower on the Mohs scale of hardness.

Let’s consider an example of five different size disks with different tolerances stacked on one another. We will calculate the overall maximum and minimum total stacked disk height using RSS Tolerance Stack up Analysis method. RSS tolerance stackup analysis for a given problem can be done in the following steps:

Stainless steel is an alloy of iron reputable for resistance to rusting and corrosion. Because stainless steel has many variations, the strength of each alloy can differ significantly. Grade 304 stainless steel, for example, stands out with incredible tensile strength of up to 621 MPa or 90 KSI.

You can also use our worst-case and RSS method tolerance stack-up calculator for tolerance stack-up calculations. You can Download Tolerance stack-up calculation sheet here.

If you think we missed Something?  You can add to this article by sending a message in the comment box. We will do our best to add it to this post.

For starters, there isn’t a universal scale for strength. At best, there are four. Keep reading to discover these four different types of strength as they relate to metallurgy. From there, you will gain better insight into metals leading the pack in terms of strength.

If you look at the results from Worst case and RSS method. In the RSS method, the tolerance band is reduced. Therefore designers can give more flexibility to manufacturers.

As you said, Mathematically standard deviation is equal to two times of process capability because the process is distributed on both sides. based on above, for ‘3 sigma’ the total tolerance of each dimension is divide by 6 (i.e. 2×3) to calculate standard deviation. but at the time of total tolerance zone calculation ‘sigma assembly’ multiplied by only 3 for ‘3 sigma’ capacity. my concern is, just like at the time of total tolerance calculation we divide each total dimension tolerance value by 6. like wise we need to multiply by 6 to ‘sigma assembly’ to get total tolerance zone. because process is distributed on both sides of mean value. please provide your feedback.

in above formula denominator (6) defines the distribution of dimensions. Denominator “6” indicates process is 3σ capable with cpk value equal to 1. If your manufacturing process is 6σ capable value ‘6’ need to be changes to 12.

Thanks Edward for your feedback. This is a linear tolerance calculator, that simply works by adding the tolerance. Here -ve sign shows the tolerance direction. So ideally output shall be irrespective of sign. So i agree with you and we will improve on this point. But at the same time, i believe it has no impact on end results as this is calculated based on cumulative values. We recommend you to also check our online tolerance calculator where we tried to over come the limitations of excel: https://www.smlease.com/entries/product-design/online-tolerance-stackup-calculator/

How should we deal with uneven tolerances (e.g. +0.1/-0.3)? Do we “normalize” it to +0.2/-0.2 (& adjust the nominal value accordingly)?

Hello, I have the same question asked by Nagaraju. So how does the worst case analysis has disadvantage over RSS method? Compared to Worst case, in RSS, you allow some parts rejection. But what about the cost of those rejected parts? How exactly RSS method is advantageous over worst case?

Tungsten and steelalloy

In the above example, the total stacked disks height / thickness will vary from 65.5 mm to 68.5 mm. We suggest you also use this calculator to calculate total disk height using worst case tolerance analysis.

What is the strongest metal on earth? It may sound like a simple question, but the answer is quite complex because comparing metals based on strength doesn’t work as you'd think. Why?

Yes; It wont help machining supplier ; However this may help to casting supplier in case wall thickness calculation. If there is a defect on casting surface and it could lead to reduction in wall thickness. Due to RSS method machining tolerance will be reduced and in result increase in wall thickness.

We suggest you read this article on Process Capability Analysis Cp and Cpk for better understanding on Statistical Tolerance Analysis.

Root sum square (RSS) tolerance stack up analysis works on a statistical approach. It is assumed that most of the parts fall to the middle of the tolerance zone.