Metal Cutting Process – Continued


Let us discuss something on how to decide the process for machining a component. To start with we should have the component drawing – also called engineering drawing. There is always a drawing called ‘Component Drawing’ for the part to be manufactured, that contains the final dimensional details of the component. This drawing provides all the details of requirement of the finally finished component and also specifies form, fit and function of the component as required finally.
Component drawing generally provides following details:






• Material:This will be with reference to some international or company standard,such as AISI (American Iron and Steel Institute), DIN (Deutsches Institut für Normung) or ISO (International Organization for Standardization). Inspection method for basic material is specified with inspection frequency. If any specific heat treatment is required for the material before it is finish machined, such details with inspection standards and method are also indicated on this drawing.

• Details:Component is generally made from some form of the desired material, like shaft, casting or sheet metal. Such details are also given on the drawing and if it is made from a pre-formed raw material like casting or forging, then the drawing for such casting, forging is also attached alongwith the component drawing.


• Form: The final form of the component after machining is shown with dimensions on the component drawing. The tolerances of the dimensions are provided, reference points for machining are also given as required. Generally, this drawing contains every detail of the component form, with identification marks, deburring requirements and surface quality requirements.

• Fit: The tolerances on the dimensions indicate the type of fit expected between this component and its mating part.

• Function: Generally, the component drawing will indicate where this component will be used and also how many such parts are required per assembly. However, the dimensionsthat are functionallyimportant for the use of the component are indicated as Critical, Major and Minor on the drawing. The dimensions with ‘C’ mark means it is functionally critical. If it is marked with ‘M’, it has major impact on function, whereas rest of the dimensions are treated as Minor.

• Inspection procedure: During machining of the component, dimensional checks are required to ensure that the component manufactured will conform to the given dimensional details. As such the inspection methods are also specified on this drawing along with frequency of inspection.

• Special Requirements: The component drawing also specifies special requirements about detection of cracks, deburring at critical areas, specific process required like paint or rust preventive, cleaning requirements with cleanliness standard.

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One Response

  1. Basic information about material, form fits and standards is important but ignored area. Having information about these factors is very much useful information. This blog will be helpful to understand micro level background and most systematic way of designing processes. Thank You and Looking forward many more blogs in future. I would like to read your upcoming blogs.

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Shrikrishna Prabhakar Vaidya

Mechanical & Electrical engineer with 33+ years experience in manufacturing engineering, particularly in metal cutting processes and machine tools.

Working as a freelance consultant in manufacturing for last 15 years.