Why do engineers use tolerances

Tolerances are pivotal in the manufacturing process because they will determine how well a part will fit in the final piece and how reliable the final product will be. We are often able to tackle vague concepts for our customers, but a challenge arises when we see differences in tolerance drawings.

When working with engineers outside of Axenics, we sometimes experience the engineer not changing the tolerance when going from a machined part to a welded part — and there will be a difference in tolerance there that is not reflected in the computer-aided-design CAD drawing provided. Fittings for a part that is welded have their own tolerance, whereas parts that are machined by a CNC machine, for example, will not have the same tolerances, because the fittings are not necessary with a bent part.

Our team can work with your designers and engineers to ensure the proper tolerances are updated. This will save time and money by reducing inspection time and manufacturing do-overs. When considering a contract metal fabricator, tolerances should be at the top of your selection criteria. Plus, by handing every aspect of your product manufacturing in-house, there is less opportunity for mistakes.

Fewer hands, fewer mistakes. In mechanical engineering, tolerance is space between bolt and nut. In other words, we can say that engineering tolerance is consideration of dimensions, properties or conditions which with some variation would not be able to affect the functioning of a system, machine or structure. So why do engineers place tolerances on dimensions? If an engineer leaves dimension without tolerance, it will result in improper fits, delay, and high cost. Tolerance is a total amount for which a particular dimension is permitted to vary.

It is the difference between maximum and minimum limits. Tolerance is giving acceptable deviation for a given dimension. Engineers place tolerance on dimensions because it provides the opportunity to manufacture individual components in different companies at different locations and enable engineers to assemble them successfully.

This article will answer the question, why do engineers place tolerances on dimensions, by considering some of the significant benefits. Going back to the question asked in the beginning, Why do engineers place tolerances on dimensions? Engineers place tolerance on dimensions to allow variances in an acceptable range in order to make a product function properly. The amount of tolerance depends on the degree of variations in a particular object.

A shallow understanding of the manufacturing process: Another common mistake is forgetting to adjust tolerances at each step of the manufacturing process. For instance, if you coat a part in primer or metal plating, then you have to make a new tolerance that takes this extra layer of material into account.

Defining tolerances requires a deep and detailed understanding of every single step in the manufacturing process and what order they are performed in. Missing tolerances: If you want to fit one part inside of another, you need to define tolerances for both of these parts. Failure to define even just one important tolerance measurement can lead to product failure down the line.

Lack of clear direction: Defining all of the necessary tolerances requires you to know which ones are important. The Number One Thing You Should Tell Manufacturers If you want to see firsthand why tolerances are important in manufacturing, you need to make sure you and your contract manufacturer are on the same page.

Ask yourself: Are there any moving parts? Do you need to make multiple parts and assemble them later? Is precision important in your industry, and if so, how important is it?

Is the weight of the product important, and if so, how much would you like it to weigh? What materials are you planning on using?

Are you particular about the color, texture, shape, or profile of your product? Pacific Research Laboratories is an experienced contract manufacturer that provides testing materials, foam products, biomedical offerings, and more to a wide range of industries.

If you need help defining tolerances for your product or refining your design for manufacturing, visit our contact page or call Tight tolerances have a narrow tolerance band. Tolerances are normal and expected, so engineers design parts with a tacit understanding that not every geometry can always be made exactly as designed. The application of a standardized approach for tolerances allows design, engineering, and manufacturing teams—no matter the location—to interpret information accurately.

Tolerances establish uniformity in specifications and reduce error opportunities, so projects can successfully transition from design to manufacturing. By applying standard tolerances to CNC machined-parts , manufacturers decrease costs, achieve higher quality deliverables, and reduce the time-to-market. Good communication between teams also depends on the use of a common language for applying tolerances.

Table 1 defines common tolerance terms. Technical drawings rely on an understanding of the different methods for defining tolerance to ensure uniformity. Table 3 exhibits how a larger number of decimal places represents a tighter tolerance.

Allows variation above and below the basic size with equal or unequal variance in either direction. It uses symbols and rules for a standardized approach to communicating dimensions.

Establishes the run-out fluctuation of a feature of a component when the component rotates on an axis. The International Organization for Standardization ISO issues globally recognized standards for overall geometrical products within the ISO standard and geometrical tolerances in machining within the ISO standard.

While ISO defines linear dimensions and angular dimensions, ISO describes geometrical tolerances according to form and position. In contrast, ISO classifies form and position according to straightness, flatness, perpendicularity, symmetry, and run. Datums and datum systems represent an exact plane, line, axis, or point location for geometric dimensioning and tolerancing.

For CNC machining, a datum translates to machine offset or Work Coordinate Systems that provide position and orientation references for the machine and the workpiece. The ISO standard addresses the terminology, rules, and methods used for datums and datum systems. CNC programming includes G code blocks that command the interpreter to move to real or absolute axis positions defined within the datum or datum systems.

Despite the lack of standard machining tolerances, different industries offer guidelines for tolerances. In most instances, those guidelines depend on the type of material required for an application, the machining method, and any plating or finishes applied to a workpiece. Precise tolerances also increase the cost of CNC machining so that project budgets can impact tolerance guidelines.

Depending on the type of application, aerospace and military projects may require precise tolerances and complex geometries.