ブロンズ加工における精度と専門知識

How to Machine Bronze: A Step-by-Step Guide

Machining bronze requires careful planning and execution. Follow these steps to achieve high-quality results and extend tool life.

Step 1: Choosing the Right Bronze Alloy

Different bronze alloys have unique properties. Leaded bronze offers excellent machinability, while aluminum bronze requires sharper tools and slower speeds. Select the alloy based on strength, wear resistance, and application needs.

Step 2: Selecting Cutting Tools

Use carbide or high-speed steel tools for bronze. Carbide lasts longer and handles more complex alloys. Sharp, high-positive rake tools reduce cutting forces and improve chip control.

Step 3: Setting Up Machining Parameters

Secure the workpiece properly to avoid vibration. Use a rigid setup with minimal tool overhang. Proper clamping ensures stability and prevents chatter during machining.

Step 4: Determining Cutting Speeds and Feeds

Maintain moderate speeds and feeds to prevent overheating. Leaded bronze allows higher speeds, while more complex alloys need slower settings. Too fast can cause tool wear, while too slow may lead to poor surface finish.

Step 5: Using Proper Coolant and Lubrication

Coolant reduces heat buildup and extends tool life. Use oil-based lubricants for better chip flow and smoother cuts. Avoid excessive coolant on leaded bronze, as it can cause built-up edge formation.

Step 6: Turning, Milling, and Drilling Bronze

For turning, use sharp inserts with high rake angles. Climb milling reduces friction and heat in milling. When drilling, use slow feeds with pecking cycles to prevent chip clogging.

Step 7: Managing Chips and Surface Finish

Bronze produces small, broken chips in free-machining grades. Complex alloys may create long, stringy control chips with proper speeds and tool geometry. Polishing or reaming improves surface finish for precision parts.

Machining Processes for Bronze

Bronze can be shaped using various machining methods. Each process has its advantages and is suited for specific applications. Here’s a breakdown of the most common techniques:

旋回

• 旋回 involves rotating the bronze workpiece while a cutting tool removes the material.
• It’s ideal for creating cylindrical parts like shafts, bushings, and fittings.
• Use sharp tools and steady speeds to achieve smooth finishes.

フライス加工

• フライス加工 uses rotating cutting tools to remove material from a stationary workpiece.
• It’s perfect for creating complex shapes, slots, and flat surfaces.
• Climb milling often works best for bronze to reduce tool wear and improve finish quality.

掘削

• 掘削 creates holes in bronze using a rotating drill bit.
• Peck drilling (drilling in small steps) helps clear chips and prevents overheating.
• Use lubricants to reduce friction and extend drill bit life.

つまらない

• つまらない enlarges or refines existing holes to precise dimensions.
• It’s commonly used for creating accurate, smooth bores in bronze parts.
• Ensure the dull tool is rigid and properly aligned for best results.

レーザー切断

• レーザー切断 uses a high-powered laser to cut intricate shapes in bronze.
• It’s ideal for thin sheets and detailed designs.
• This method offers high precision and minimal material waste.

EDM Processing

• ED uses electrical sparks to shape bronze.
• It’s suitable for complex geometries and hard-to-reach areas.
• EDM is precise but slower than traditional machining methods.

Tooling Considerations for Bronze Machining

Selecting the right tools dramatically affects your success with bronze machining. Making smart tooling decisions leads to better parts with less effort.

Best tool materials for machining bronze

The proper cutting tools make bronze machining more efficient and produce better surface finishes. Tool material and geometry both play important roles in tool performance.

Several tool materials work well with bronze, each with advantages:

• Uncoated carbide tools work excellently for most bronze machining. The sharp cutting edges slice through bronze cleanly without excessive heat.
• HSS tools provide good performance at a lower cost. They are well-suited for small shops and occasional bronze machining.
• Diamond-coated tools excel in high-production environments. They last much longer than uncoated tools, offsetting their higher initial cost.
• PCD tools offer the most extended life for high-volume production. Their hardness is highly resistant to wear from abrasive bronze alloys.
• Ceramic tools are generaaren’tt recommended for bronze work. They lack the necessary toughness and offer few advantages over carbide.

For tool coatings, TiN provides good wear resistance for bronze machining. However, many machinists prefer uncoated tools for bronze since they maintain sharper cutting edges.

Cutting Speeds and Feeds

Proper speeds and feeds prevent work hardening and tool damage while maximizing productivity. The correct parameters vary by bronze type and tool material.

Optimal parameters for different bronze alloys

Cutting speeds for common bronze alloys (with carbide tooling):

Leaded bronze (C83600):

• Turning: 400-600 SFM
• Milling: 350-550 SFM
• Drilling: 250-400 SFM

Phosphor bronze (C51000):

• Turning: 250-400 SFM
• Milling: 200-350 SFM
• Drilling: 150-250 SFM

Aluminum bronze (C95400):

• Turning: 150-300 SFM
• Milling: 125-250 SFM
• Drilling: 100-200 SFM

Silicon bronze (C87300):

• Turning: 200-350 SFM
• Milling: 175-300 SFM
• Drilling: 125-225 SFM

For HSS tooling, reduce these speeds by 40-50%.

Feed rates also vary by operation:

• Turning: 0.” 05-0.015″ per revolution for finishing, 0. “10-0.030” for roughing
• Milling: 0. “03-0.008″ per tooth for finishing, 0.” 05-0.015″ for roughing
• Drilling: 0. “02-0.008” per revolution, depending on drill diameter

These ranges provide starting points. Adjust based on your specific machine, tool condition, and workpiece requirements.