PC Injection Molding Temperature: The Complete Guide

Getting the PC injection molding temperature right can make or break your parts.

I’ve seen it happen countless times. A manufacturer sets their polycarbonate processing temperature too low, and suddenly they’re dealing with short shots and weak parts. Or they crank it too high and end up with degraded material and silver streaks everywhere.

The truth is:

Nailing the right temperature settings for PC isn’t just about following a spec sheet. It’s about understanding how temperature affects every aspect of your molding process.

In this guide, as a professional PC injection molding manufacturer, I’ll show you exactly how to optimize your PC injection molding temperatures for perfect parts every time.

What Temperature Should You Use for PC Injection Molding?

Here’s the quick answer:

PC typically requires barrel temperatures between 260°C and 320°C (500°F to 608°F).

But that’s just the starting point.

The exact temperature you need depends on several factors:

Your specific PC grade
Part complexity
Mold design
Production requirements

Let me break this down further.

Understanding PC Processing Temperatures

Polycarbonate is what we call a “temperature-sensitive” material.

What does this mean?

Unlike some plastics that have a wide processing window, PC demands precision. The material’s viscosity drops significantly as temperature increases, but push it too far and you’ll start seeing decomposition.

The Temperature Sweet Spot

Most PC grades process best at a melt temperature between 275°C and 295°C.

This is the actual temperature of the molten plastic (not just what your barrel controller shows).

But here’s where it gets interesting:

Your barrel temperature settings need to create a specific temperature profile.

Setting Up Your Barrel Temperature Profile

The key to processing PC successfully?

Creating the right temperature gradient from feed to nozzle.

Here’s what works:

Rear Zone (Feed): 250-270°C
Center Zone: 260-270°C
Front Zone: 270-290°C
Nozzle: 270-290°C

Notice the pattern?

You want a gradual increase from back to front. This ensures the material melts progressively without degrading.

Pro Tip: Measure Your Actual Melt Temperature

Don’t trust your machine’s display blindly.

Use a pyrometer to check your actual melt temperature by taking an air shot. This tells you what’s really happening with your material.

Why Mold Temperature Matters Just as Much

Here’s something most people overlook:

Your mold temperature is just as critical as your barrel temperature.

For PC, you want to maintain mold temperatures between 80°C and 120°C (176°F to 248°F).

Why so high?

PC needs elevated mold temperatures to:

Achieve proper surface finish
Minimize internal stress
Ensure dimensional stability
Prevent warpage

I’ve seen parts with perfect mechanical properties fail simply because the mold was too cold.

The Hidden Danger: Moisture

Before we go any further, let’s talk about PC’s biggest enemy:

Water.

Polycarbonate is hygroscopic. It sucks moisture from the air like a sponge.

And when you heat wet PC to processing temperature?

You get hydrolysis. The material literally breaks down, causing:

Bubbles
Silver streaks
Weak parts
Surface defects

The solution?

Pre-dry your material at 120°C (248°F) for 4-6 hours. Keep moisture content below 0.02%.

No exceptions.

Grade-Specific Temperature Guidelines

Not all PC grades are created equal.

Different formulations require different processing parameters:

Standard PC Grades

Barrel temperature: 280-300°C
Mold temperature: 85-95°C
Best for general-purpose applications

High-Flow PC

Barrel temperature: 260-280°C
Mold temperature: 80-90°C
Ideal for thin-wall parts

Glass-Filled PC

Barrel temperature: 290-310°C
Mold temperature: 90-110°C
Requires higher temperatures due to increased viscosity

PC/ABS Blends

Barrel temperature: 240-280°C
Mold temperature: 70-100°C
Lower processing temperature than pure PC

Always check your material supplier’s data sheet. But use these as your starting points.

Temperature’s Impact on Part Quality

Temperature doesn’t just affect whether your mold fills.

It impacts everything:

Surface Finish

Higher mold temperatures = better surface gloss. I’ve seen parts go from matte to mirror-like just by raising mold temperature 20°C.

Dimensional Stability

Proper temperature control minimizes shrinkage variation. This is crucial for precision parts.

Mechanical Properties

Too low? You get weak weld lines and poor impact strength.
Too high? Material degradation reduces overall properties.

Internal Stress

This is the big one. Incorrect temperatures create internal stress that leads to:

Cracking
Warpage
Part failure in service

The key is finding the balance between good flow and minimal stress.

Let me share the most common issues I see:

Silver Streaks

Cause: Moisture or overheating
Fix: Dry material properly, reduce barrel temperature

Short Shots

Cause: Temperature too low, poor flow
Fix: Increase barrel temperature 10°C, check nozzle temperature

Burn Marks

Cause: Excessive temperature or residence time
Fix: Lower temperatures, reduce cycle time

Poor Weld Lines

Cause: Melt temperature too low at flow front
Fix: Increase barrel and mold temperature

Warpage

Cause: Uneven cooling, internal stress
Fix: Optimize mold temperature uniformity

Advanced Temperature Control Strategies

Want to take your PC molding to the next level?

Try these advanced techniques:

Zone-Specific Optimization

Don’t just set it and forget it. Fine-tune each zone based on:

Screw design
Material throughput
Part requirements

Dynamic Temperature Control

Some applications benefit from varying mold temperature during the cycle. This requires specialized equipment but can dramatically improve part quality.

Hot Runner Considerations

Running PC through hot runners? Keep temperatures 5-10°C higher than your nozzle to prevent freeze-off.

Setting Up Your Process: Step by Step

Here’s my proven process for dialing in PC temperatures:

Start with material prep
- Dry material to <0.02% moisture
- Keep in sealed containers
Set initial temperatures
- Use manufacturer recommendations
- Start conservative
Warm up properly
- Allow 30 minutes for temperature stabilization
- Run purge cycles
Take test shots
- Check fill pattern
- Measure actual melt temperature
Optimize incrementally
- Adjust in 5°C increments
- Document changes
Validate part quality
- Check dimensions
- Test mechanical properties

Troubleshooting Temperature Issues

When things go wrong (and they will), here’s your troubleshooting checklist:

Part won’t fill completely?

Check nozzle isn’t frozen
Increase barrel temperature
Verify mold temperature

Seeing degradation?

Reduce barrel temperature
Check residence time
Clean screws and barrels

Inconsistent dimensions?

Verify temperature stability
Check mold temperature uniformity
Review cooling time

Equipment Considerations for PC Processing

Not all injection molding machines are created equal for PC.

You need:

Precise temperature control (±1°C)
Adequate heating capacity
Good screw design for PC
Proper instrumentation

Older machines might struggle. If you’re serious about PC, invest in proper equipment.

The Economics of Temperature Control

Here’s something to consider:

Running at optimal temperatures might use more energy (higher mold temperatures especially).

But the payoff includes:

Fewer rejects
Better part quality
Reduced post-processing
Happier customers

Do the math. Quality pays.

Future Trends in PC Processing

As we move through 2025, I’m seeing new developments:

Smart temperature control systems using AI
More energy-efficient heating methods
Better insulation technologies
Real-time viscosity monitoring

Stay ahead of the curve.

Key Takeaways

Let’s wrap this up with the essentials:

PC requires precise temperature control for success
Barrel temperatures typically range 260-320°C
Mold temperature (80-120°C) is equally critical
Always pre-dry material to prevent degradation
Different grades need different temperatures
Monitor and adjust based on part quality

Remember:

Success with PC injection molding temperature isn’t about following a recipe blindly. It’s about understanding the principles and adapting to your specific situation.

Start with the guidelines I’ve shared. Test systematically. Document what works.

Before long, you’ll be producing perfect PC parts consistently.

That’s the power of mastering temperature control in polycarbonate injection molding.