The component that supports the compressor and connects it to the engine is our focus we’ll call it the “compressor base”. Figure 1 shows a vehicle engine with a compressor for AC. In order to understand the content of this standard and its parts, it’s best to use a real world example. Such instances are normal, and not uncommon, so you should always check the drawing title block for general tolerance requirements and note any special part specifications or project requirements.

The standard is made of general rules because there are exceptions when a dimension on a part needs a tighter tolerance than those set by ISO 2768.

By including the ISO 2768 specification, you are simplifying your drawing, and avoiding writing tolerances for every dimension and feature. Geometrical tolerances for features with precision levels defined as tolerances classes: H, K, and Lįor example, a drawing could be specified as ISO 2768-mK, which means it should meet the tolerances ranges for “medium” from Part 1 and tolerance class “K” from Part 2.

General tolerances for linear and angular dimensions with precision levels defined as f-fine, m-medium, c-coarse, v-very coarse (also known as the four tolerance classes in DIN ISO 2768).

ISO 2768 is divided into two parts that aim to simplify drawings by defining precision levels as general rules: And because it’s the global industry standard, Fictiv’s CNC machining service adheres to ISO 2768 medium requirements. It is an international manufacturing standard that can not only help to determine standard machining tolerances, but also minimize inconsistencies while accounting for manufacturing costs as well.īecause the standard was created by an international committee, it puts you on the same page as companies all around the world to prevent misunderstandings. ISO 2768 provides general standard metric tolerances (mm) for linear and angular dimensions without individual tolerance indications in four tolerance classes. A circularity tolerance would tell you if the non-perfect circular bar shapes are acceptable. The Lesson: an engineering drawing tolerance would tell you if the measured values above are within the acceptable range for the diameter dimension. The bars also vary in length and upon closer inspection, they’re not perfectly circular.Ĭan you still use them? If not, can you reject them and demand that the vendor redo them at no cost? How close to the Ø50mm should you really be?

Upon measuring the finished bars, you get values like Ø53mm, Ø47mm, Ø51mm, Ø49mm, equating to a range of a diameter of 47-53mm.

You order 200 of these Ø50mm rounds bars.

Object to be manufactured: a round solid bar of 100mm length with Ø50mm that will fit inside of a hole in another component.

Iso 2768 mk standard free download