Machining Technology of C17200 Precipitation-Hardened Beryllium Copper Alloy

Summary

This article presents the machining techniques for C17200 precipitation-hardened beryllium copper alloy. It covers machining characteristics, cutting tool selection, tool geometry, machining parameters, coolant selection, as well as milling and drilling practices. Drawing from years of processing experience, the methods described have enabled the successful application of C17200 in demanding environments such as oilfield logging tools.

1. Material Overview

C17200 is a Cu-Be alloy that, after solution and aging treatment, exhibits:

• High hardness (38–44 HRC), strength, and fatigue limit

• Good corrosion resistance, electrical conductivity, and non-magnetic behavior

• Excellent performance in extreme environments (low/high temperature, high pressure, acidic media)

  It is especially suitable for components in oilfield logging instruments.

2. Machining Characteristics of C17200

• Work Hardening: Rapid hardening during cutting; hardened layer ≥ 0.007 mm

• High Cutting Force: Due to elevated strength and hardness

• Low Modulus of Elasticity: About 128 GPa, prone to deflection

• Severe Tool Wear: Caused by oxide film, high cutting temperature, and plastic deformation

3. Cutting Tool Selection

• Preferred Tool Material: Cemented carbide (e.g., YG6, YG8)

• Avoid: YT series tools due to affinity and adhesion wear

• HSS tools: Usable but inferior in thermal resistance and wear life compared to carbide

4. Recommended Tool Geometry

• Edge Shape: Rounded edge, radius rε = 0.1–0.8 mm

• Chamfering: Negative chamfer γo1 = –10° to –5°, width bγ1 = 0.3–0.8 × f

• Chipbreaker: Arc-shaped grooves, radius Rn = 2–7 × f

• Rake Angle (γo): 5°–10°

• Relief Angle (αo): 6°–8°

• Lead and Secondary Angles (κr/κ’r): 45°–75° and 5°–10°

• Inclination Angle (λs): –10° to –5° (roughing); 0° (finishing)

5. Machining Parameters

• Cutting Speed (vc): 100–200 m/min

• Depth of Cut (ap): 0.05–3 mm

• Feed Rate (f): 0.1–0.15 mm/rev

6. Coolant and Lubrication

• Coolant Type:

  • Avoid: Emulsions with sulfur (may stain surface)

  • Recommended: Mineral oil + 3–7% lard — good lubrication, acceptable cooling

  
  

• Main Function: Reduce cutting temperature, prolong tool life

7. Milling C17200

• Tool Choice: Cemented carbide end mills preferred

• Method: Asymmetric climb milling reduces friction and vibration

• Coolant Use: Helps reduce surface roughness and tool wear

8. Drilling C17200

• Tool: HSS twist drill, helix angle 29°, point angle 118°, chisel angle 12°

• Technique:

  • Use cutting fluid continuously

  • Maintain stable cutting speed and feed

  • Prevent chip buildup and surface scratching

  • Avoid bottom hardening of holes