1. What is Speed and Feed for Plastic?

Definition: This calculator determines the optimal spindle speed (RPM) and feed rate (IPM) for machining plastic materials.

Purpose: It helps machinists and CNC operators achieve efficient material removal while preventing damage to plastic workpieces.

2. How Does the Calculator Work?

The calculator uses two formulas:

Where:

• \( RPM \) — Spindle speed (revolutions per minute)
• \( SFM_{plastic} \) — Surface feet per minute for plastic
• \( D \) — Tool diameter (inches)
• \( IPM \) — Feed rate (inches per minute)
• \( IPT \) — Inches per tooth (chip load)
• \( Z \) — Number of teeth on the cutter

Explanation: The first formula calculates spindle speed based on material properties and tool size. The second determines feed rate based on speed, tooth count, and desired chip load.

3. Importance of Proper Speed and Feed

Details: Correct settings prevent melting, chipping, poor surface finish, and tool breakage while optimizing machining efficiency.

4. Using the Calculator

Tips: Enter SFM (varies by plastic type), tool diameter, chip load (IPT), and number of teeth. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical SFM for plastics?
A: Varies by material: 300-600 for acrylic, 200-400 for PVC, 150-300 for nylon. Always consult material specs.

Q2: Why is 3.82 used in the RPM formula?
A: It's the conversion factor (12/π) to convert SFM (feet/min) to RPM with diameter in inches.

Q3: How do I determine IPT for plastics?
A: Start with 0.001-0.010 in/tooth depending on plastic type and tool size, then adjust based on results.

Q4: Should I use different settings for different plastics?
A: Yes, thermoplastics generally need higher SFM than thermosets, and brittle plastics need lower IPT.

Q5: What if I get melting or poor finish?
A: Try increasing RPM (higher SFM), reducing IPT, or using sharper tools with proper clearance angles.