General role of drawings

The function of a drawing is to express information, allowing relevant personnel to confirm and understand the information of the manufactured parts. For detailed explanation, we have divided its functions into four categories.
① Present part shape
By using projection methods such as the third triangle method to draw the shape of the part from the main view, top view, and side view onto the drawing, it is possible to accurately convey the shape information of the part to third parties.
In addition, as needed, for parts that cannot be represented by relying on three views, accurate communication can be achieved by adding "sectional views", "detailed drawings", "isometric projection drawings", etc.
② Procurement arrangement of parts
When purchasing and arranging parts, drawings should be used. This is because it is necessary to communicate 100% to the other party what part shape to make. Due to the fact that the procurement department uses drawings to consult with manufacturers about the possibility of production or obtaining quotations, sometimes different drawing methods can cause significant changes in the quoted amount. For example, if the 'dimensional tolerance' requirement is strict, even if the parts have the same shape, the quoted amount will significantly increase.
③ The role of the contract
Due to the use of drawings by the procurement department to arrange the procurement of parts, the drawings also serve as contract documents. This is because the parts need to be manufactured according to the drawings. If the dimensions and other parameters do not match the drawings, the parts can be rejected as violating the contract.
④ Function of measurement instruction book
The drawing specifies parameters such as "dimensional tolerance", "geometric tolerance", and "surface roughness". For example, "geometric tolerance" implies the measurement method of the part, so the drawing also serves as a measurement instruction book. If a tolerance is specified using 'geometric tolerance', it is equivalent to indicating 'please use measuring fixtures and dial indicators to measure while rotating the part'.