Precision CNC Machining: Tolerances and Measurement Techniques Explained

77 Teknik
Jul 25
2 min read

Updated: Aug 18

Precision CNC Machining — *Dimensional drawing showing bilateral and unilateral tolerances.*

What Are Machining Tolerances and Why Are They Crucial?

CNC machining tolerances define how much variation is acceptable in a part's dimensions. These small allowances are key to ensuring functionality, performance, and interchangeability in precision components.

Main Takeaways:

Tolerances allow for realistic manufacturing variation.
The tighter the tolerance, the more precise (and often expensive) the process.
Defining the right tolerance early on improves quality and reduces cost.

Types of CNC Machining Tolerances

Understanding the different types of tolerances helps designers and engineers align their requirements with machining capabilities.

Unilateral Tolerances: Variation in one direction only (e.g., -0.00 / +0.10 mm)
Bilateral Tolerances: Variation allowed in both directions (e.g., ±0.02 mm)
Limit Tolerances: Explicit upper and lower limits (e.g., 9.95 mm to 10.05 mm)

The Impact of Tolerances on Functionality and Cost

Performance: Incorrect tolerances may lead to poor fits or mechanical failure.
Assembly: Proper tolerances allow for seamless integration with other components.
Cost Efficiency: Tighter tolerances require more time, specialized tooling, and advanced inspection — increasing overall production costs.

Measurement Techniques in Precision CNC Machining

At 77 Teknik, we ensure precision cnc machining through a range of professional-grade inspection tools and techniques:

1. Digital Calipers & Micrometers

Quick checks for external and internal dimensions ideal for small-to-medium parts.

2. Coordinate Measuring Machines (CMM)

3D probing system for highly complex parts and tight tolerances.

3. Go/No-Go Gauges

Fast pass/fail checks to ensure dimensional conformity in mass production.

4. Optical Inspection & Profile Projectors

Used for visual verification of contours, holes, and threads.

5. Surface Roughness Testers

Evaluate finishing quality critical in automotive, medical, and aerospace applications.

77 Teknik’s Quality Assurance Approach

Our commitment to accuracy and reliability includes:

In-Process Inspections
Detailed Quality Reports (PPAP, Control Plans, FAI)
ISO-Compliant Quality Management
Advanced Metrology Tools
Expert Technical Support

How Tolerance Management Boosts Product Reliability

Good tolerance management isn’t just about hitting numbers it builds better products.

Reduces rework and scrap
Improves part longevity and safety
Enhances customer satisfaction

Ready for High-Precision CNC Solutions?

At 77 Teknik, we deliver CNC parts that meet the tightest tolerances using cutting-edge machining and inspection processes. Whether it’s for aerospace, medical, automotive, or industrial components precision is in our DNA.