In precision machining, technical drawings determine nearly all of the cost, lead time, and machining difficulty. Below are the four most important factors:
1. GD&T accuracy:
The tighter the GD&T specifications—such as flatness, concentricity, and positional tolerance—the more machine setup and adjustment are required. Inspection time increases, and the risk of scrap also rises, leading to higher production costs.
2. Tolerances:
The smaller the tolerance and the higher the required accuracy, the more advanced equipment is needed and the longer the machining time. As a result, the unit price increases compared to drawings with standard tolerances.
3. Corner radius (R) cannot be zero:
Cutting tools always have a radius. If a perfectly sharp corner is specified, special processes such as wire-cut EDM or other non-standard machining methods are required.
→ This increases machining time and leads to higher unit costs.
4. Level of machining difficulty:
Hard materials, complex surfaces, thin or low-rigidity parts, and components requiring special fixturing all contribute to increased manufacturing costs.
Therefore, a well-designed drawing can reduce machining costs by 10–40% while improving product quality. For this reason, during the quotation process, Yumoto Vietnam consults with customers and proposes drawing adjustments—within allowable limits—to optimize costs as effectively as possible.
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