1. What is Feeds and Speeds for Plastic?

Definition: This calculator determines optimal machining parameters (spindle speed and feed rate) when cutting plastic materials.

Purpose: Helps machinists and CNC operators achieve clean cuts in plastic materials while maximizing tool life and efficiency.

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 and tool size. The second calculates feed rate based on spindle speed, chip load, and number of teeth.

3. Importance of Proper Feeds and Speeds

Details: Correct feeds and speeds prevent melting, chipping, poor surface finish, and tool breakage when machining plastics.

4. Using the Calculator

Tips: Enter the SFM for your plastic material, 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 plastic type: 300-600 for acrylic, 200-400 for PVC, 150-300 for nylon. Always check 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?
A: Consult tool manufacturer recommendations or start with 0.001-0.010" for plastics and adjust based on results.

Q4: What if my tool has only one tooth?
A: Set Z=1. Single-flute tools are common for plastic machining to reduce heat buildup.

Q5: Should I adjust for different plastic types?
A: Yes. Softer plastics can handle higher SFM, while brittle plastics may need slower speeds.