Injection Mold Cooling - Temperature Control Systems and Optimization 2025

Introduction - 60-70% of cycle time is cooling

Injection Mold Cooling is the most undervalued element of the plastics injection molding process. It accounts for 60-70% of total production cycle time, yet many companies pay it minimal attention during production optimization.

A typical injection molding plant in Poland loses 200,000-500,000 PLN annually due to inefficient mold cooling. The problem isn't obvious at first glance - molds run, parts come out of the machine. But the hidden costs include:

• Extended cycle time - 5-15 s seconds longer per cycle (at 50,000 cycles per month = 70-210 hours of lost machine time)
• Thermal defects - warpage, sink marks, internal stresses - account for 25-40% of all rejects
• Dimensional instability - tolerances ±0,15 mm instead of ±0,05 mm, complaints from automotive customers
• Higher energy use - inefficient systems consume 15-30% more energy for cooling

Good news? Companies that implemented systematic cooling optimization on Tederic injection molding machines report cycle time reductions of 25-45% and thermal reject reductions of 60-80% within 3-6 m months. This guide provides specific parameters, a case study from a Polish company, and a diagnostic matrix for cooling issues.

What is injection mold cooling?

Injection mold cooling is the controlled process of removing heat from the plastic in the mold cavity. The process involves flowing coolant (water, oil, or CO₂) through a network of cooling channels machined into the mold plates, which absorb heat from the molten plastic (180-350°C) and dissipate it to the outside.

Key cooling process parameters:

• Mold temperature - controlled to ±1-2°C for dimensional repeatability
• Coolant flow rate - 10-60 l/min per circuit, turbulent flow (Re > 10,000) for efficient heat transfer
• Temperature differential ΔT - optimal 2-4°C between supply and return
• Cooling time - 50-70% of total cycle, determined by wall thickness and ejection temperature

Modern temperature control systems equipped with PID controllers (Proportional-Integral-Derivative) ensure thermal stability even under varying production conditions - different wall thicknesses, ambient temperature changes, plant water pressure fluctuations.

Types of Cooling Systems

Today's injection molding industry offers 4 main types of mold cooling systems, differing in coolant, temperature range, and operating costs.

Water Cooling - 70% of all installations

Water cooling is the most common system, using demineralized water or glycol as coolant. Temperature range: 5-90°C.

Advantages:

• Highest cooling efficiency - water has specific heat capacity of 4,18 kJ/kg·K (4x higher than oil)
• Low operating costs - demineralized water 5-10 PLN/m³, glycol 20-30 PLN/liter
• Fast thermal response - low viscosity ensures turbulent flow
• Safety - non-flammable and non-toxic

Disadvantages:

• Temperature limitation - max 90-95°C (risk of vaporization)
• Corrosion - requires inhibitors, demineralization (hardness < 5°dH), pH control (7.0-8.5)
• Deposits and scaling - requires periodic citric acid flushing

When to use: 80% of applications - PP, PE, ABS, PS, PMMA, PC (up to 90°C). Ideal for packaging, appliance parts, electronics.

Oil Cooling - for high temperatures 90-300°C

Oil cooling uses thermostat oil, enabling operation in the 90-300°C range. Used for crystalline plastics requiring high mold temperatures.

Advantages:

• Wide temperature range - no vaporization risk
• No corrosion - no inhibitors needed
• Thermal stability - synthetic oils retain properties

Disadvantages:

• Lower efficiency - specific heat capacity 1.8-2,5 kJ/kg·K (half that of water)
• High costs - oil 25-50 PLN/liter, replacement every 2-3 l years
• Fire risk - flash point 200-320°C
• Higher energy costs - heating to 150-200°C requires 3-5 kW continuous power

When to use: POM (90-120°C), PA6/PA66 (80-110°C), PBT (90-130°C), PPS (130-160°C), PEEK (180-220°C). Automotive technical parts, bearings, gears.

Conformal Cooling - 20-50% Cycle Time Reduction

Conformal cooling is a revolutionary technology where cooling channels precisely follow the part geometry contour, maintaining a constant 8-15 mm distance from the forming surface. Achieved via metal 3D printing (DMLS, SLM).

Dramatic benefits:

• 20-50% reduction in cooling time - uniform heat removal
• 50-80% elimination of warpage - no shrinkage differentials
• Better surface quality - no cold spots
• 40-60% lower internal stresses
• ROI in 12-24 m months for production > 50,000 s parts annually

Costs: Metal 3D printed inserts 30,000-150,000 PLN (5-10x more expensive than traditional drilling), but efficiency savings pay back the investment in 1-2 l year.

Cooling Issue Diagnostics - Solutions Matrix

This diagnostic matrix lets you quickly identify cooling problems and implement the right solutions. 85% of thermal issues fall into these 6 categories.

Problem 1: Extended cycle time (> 40% of total cycle)

• Symptoms: Part requires long cooling, warps if ejected early
• Causes: Mold temperature too high, inefficient channels, low flow
• Tederic Solution: Lower mold temperature by 10-15°C, increase flow by 20-30%, check ΔT (should be 2-4°C)
• Parameters: Controller temperature: -10°C from current, Flow: +5 l/min

Problem 2: Warpage > 0,5 mm/100 mm

• Symptoms: Part warps after ejection, asymmetrical dimensions
• Causes: Uneven cooling, different mold side temperatures, holding time too short
• Tederic Solution: Balance cavity and core temperatures (max difference 5°C), extend holding time by 15-20%
• Parameters: Cavity temp: 55°C, Core temp: 52°C (for PP), Holding time: +2-3 s seconds

Problem 3: Sink marks depth > 0,1 mm

• Symptoms: Depressions on surface over ribs or thick sections
• Causes: Surface cooling too fast, insufficient holding pressure, walls too thick
• Tederic Solution: Increase mold temperature by 10°C, boost holding pressure by 10-15%, extend holding time
• Parameters: Mold temp: +10°C, Holding pressure: from 400 bar → 450 bar, Holding time: +3 s

Problem 4: Visible weld lines

• Symptoms: Visible lines where melt streams meet on the part
• Causes: Mold temperature too low, injection speed too slow
• Tederic Solution: Raise mold temperature by 15-20°C, increase injection speed by 20%
• Parameters: Mold temp: from 50°C → 65-70°C (for ABS), Injection speed: from 80 mm/s → 100 mm/s

Problem 5: Internal stresses (post-assembly cracks)

• Symptoms: Part cracks after weeks/months in use, especially with oils/solvents
• Causes: Mold temperature too low, cooling time too short, rapid solidification
• Tederic Solution: Increase mold temperature by 20-30°C, extend cooling time by 25%
• Parameters: Mold temp: from 40°C → 60-70°C (for PC), Cooling time: +5-8 s

Problem 6: Dimensional instability (tolerances > ±0,1 mm)

• Symptoms: Part dimensions vary between cycles
• Causes: Mold temperature fluctuations > ±3°C, unstable coolant flow
• Tederic Solution: Check temperature controller (should hold ±1°C), replace filter, inspect pumps
• Parameters: Stability: ±1°C, Flow: constant (monitor return pressure)

Parameter Optimization on Tederic Injection Molding Machines

Tederic injection molding machines feature advanced temperature monitoring and control systems for precise cooling optimization. Here's a step-by-step guide to optimizing cooling on a Tederic machine.

Step 1: Audit Current Cooling System

• Measure mold temperature at 4-6 points (IR thermometer or thermocouples)
• Record ΔT on controller (supply vs return)
• Measure coolant flow with flowmeter (l/min)
• Determine current cooling time and total cycle time
• Goal: Identify deviations from optimal values

Step 2: Optimize Flow (most common issue)

• Rule: ΔT should be 2-4°C
• If ΔT > 5°C → increase flow by 20-30%
• If ΔT < 1°C → reduce flow (pump energy savings)
• On Tederic: Set pump pressure to 4-6 bar, monitor on HMI screen
• Typical values: 15-25 l/min for small molds, 25-40 l/min for medium, 40-80 l/min for large

Step 3: Match Temperature to Material

• Configure temperature controller per table in "Parameters for 8 Key Plastics" section
• On Tederic controller, set tolerance to ±1°C for crystalline plastics, ±2°C for amorphous
• Enable HIGH/LOW TEMP alarms at ±5°C from setpoint
• Tederic Feature: Use built-in thermal profiles for common plastics

Step 4: Balance Cavity/Core Temperatures

• For asymmetrical parts: set cavity temperature 2-5°C higher than core
• Monitor warpage - if part warps toward cavity, lower its temperature
• On Tederic: Use two independent cooling circuits (multi-zone option)
• Save parameters in machine memory for each mold

Step 5: Optimize Cooling Time

• Rule of thumb: t_cool = (wall thickness [mm])² × 2 s seconds (for PS, ABS at 60°C)
• Start from theoretical value, reduce by 1-2 s every 10 cycles
• Stop when warpage occurs or part sticks in mold
• On Tederic: Use "Cycle Time Optimization" function - automatic suggestions
• Typical reduction: 15-25% from initial setting

Step 6: Documentation and Monitoring

• Save optimal parameters in MES system or spreadsheet
• Set automatic alerts for deviations > ±3°C or ΔT > 6°C
• On Tederic: Use OPC-UA protocol for plant system integration
• Analyze temperature trends weekly - detect system degradation

Cooling Parameters for 8 Key Plastics

The table below contains specific cooling parameters for the most commonly processed plastics. Values optimized for Tederic injection molding machines with industrial-grade temperature controllers.

PP (Polypropylene) - 35% of the injection molding market

• Mold temperature: 40-80°C (typically 50-60°C)
• System: Water with 6-9 kW controller
• Flow: 20-30 l/min per circuit
• Cooling time: 18-25 s for 3 mm wall
• ΔT optimal: 3-4°C
• Notes: High shrinkage 1.5-2,5% - uniform cooling required, conformal cooling recommended for large parts
• Tederic Parameters: Controller 55°C ±2°C, alarm ±5°C, "PP Standard" profile

HDPE/LDPE (Polyethylene) - 25% market

• Mold Temperature: 20-50°C (lower than most plastics)
• System: Water with chiller up to 25-35°C
• Flow: 40-60 l/min (high for fast heat removal)
• Cooling Time: 10-18 s for 3 mm (shortest)
• ΔT optimal: 2-3°C
• Notes: High productivity thanks to low mold temperature
• Tederic Parameters: Controller 30°C ±2°C + chiller, "PE Fast Cycle" profile

ABS (Acrylonitrile-Butadiene-Styrene) - 15% market

• Mold Temperature: 50-80°C (typically 60-70°C)
• System: Standard water
• Flow: 25-35 l/min
• Cooling Time: 20-30 s
• ΔT optimal: 3-4°C
• Notes: Uniform cooling critical for surface quality, conformal cooling for aesthetic parts
• Tederic Parameters: Controller 65°C ±2°C, "ABS Aesthetic" profile

PC (Polycarbonate) - 8% market

• Mold Temperature: 80-120°C (typically 90-100°C)
• System: Water up to 95°C or oil above 100°C
• Flow: 20-30 l/min
• Cooling Time: 30-50 s (long)
• ΔT optimal: 3-4°C
• Notes: Precise ±1°C control prevents internal stresses
• Tederic Parameters: Controller 95°C ±1°C, "PC Optical" profile for clear parts

PA6/PA66 (Nylon) - 7% market

• Mold Temperature: 80-110°C
• System: Oil for > 95°C or water up to 90°C
• Flow: 25-35 l/min
• Cooling Time: 25-40 s
• ΔT optimal: 3-5°C
• Notes: Higher temperature = higher crystallinity and strength, lower = shorter cycle
• Tederic Parameters: Oil controller 95°C ±2°C, "PA Technical" profile

POM (Delrin, Acetal) - 4% market

• Mold Temperature: 90-120°C (one of the highest)
• System: Oil mandatory
• Flow: 20-30 l/min
• Cooling Time: 35-60 s (long)
• ΔT optimal: 3-4°C
• Notes: Highly sensitive to uniformity - uneven causes cracking
• Tederic Parameters: Oil controller 105°C ±1°C, "POM Precision" profile

PET (Polyethylene Terephthalate) - 4% market

• Mold Temperature: 10-40°C (bottles) or 120-140°C (preforms)
• System: Water with chiller or oil
• Flow: 80-120 l/min (bottles) or 25-35 l/min (preforms)
• Cooling Time: 12-20 s (bottles) or 40-70 s (preforms)
• ΔT optimal: 2-3°C
• Notes: Very fast cycles for bottles, cooling critical
• Tederic Parameters: Controller 15°C + chiller, "PET Bottle Fast" profile

PEEK (high-performance) - 2% market

• Mold Temperature: 180-220°C (highest)
• System: High-temperature oil only
• Flow: 15-25 l/min
• Cooling Time: 60-120 s (very long)
• ΔT optimal: 4-6°C
• Notes: Extreme temperatures, energy costs 3-5x higher, aerospace, medical
• Tederic Parameters: Synthetic oil controller 200°C ±2°C, "PEEK High-Temp" profile

Case Study: Cycle Time Reduction by 43% - Greater Poland Company

Here's a real case study of a Polish company that optimized mold cooling on Tederic injection molding machines, achieving dramatic savings.

Company: Cosmetic packaging manufacturer from Greater Poland region
Product: PP jars 50m l with lid (2 molds, 8 cavities each)
Machines: 2x Tederic D120
Annual Production: 2,400,000 sk parts

Status Before Optimization:

• Cycle Time: 28 s (incl. cooling 18 s = 64%)
• Mold Temperature: 45°C (water controller without optimization)
• ΔT: 8°C (too high - inefficient cooling)
• Flow: 12 l/min (too low)
• Thermal Defects: 4,2% (warpage, sink marks)
• Monthly Production: 154,000 sk parts (6000h / month × 8 cavities)

Implemented Changes:

Phase 1: Cooling System Audit (Week 1)

• Mold temperature measurement at 8 points - identified unevenness ±8°C between cavities
• Cooling channel analysis - detected limescale deposits in 3 channels (flow drop 40%)
• Controller check - PT100 sensor offset by +3°C (erroneous readings)

Phase 2: Maintenance and Repairs (Week 2)

• Citric acid flushing 10% for 6 hours - deposits removed
• Filter cartridge replacement (clogged at 70%)
• PT100 sensor calibration (offset < 0,5°C)
• Cost: 2,500 PLN (labor + materials)

Phase 3: Parameter Optimization Tederic (Week 3)

• Increased flow: 12 l/min → 28 l/min (new pump 0,75 kW → 1,5 kW)
• Reduced mold temperature: 45°C → 38°C (faster PP solidification)
• ΔT after optimization: 8°C → 3°C (effective heat exchange)
• "PP Fast Cycle" profile set on Tederic controller
• Cost: 3,800 PLN (pump) + 1,200 PLN (setup)

Phase 4: Cycle Time Optimization (Week 4)

• Gradual cooling time reduction: 18 s → 14 s → 10 s (quality monitoring)
• Holding pressure adjustment: +8% pressure to eliminate sink marks with shorter cooling
• New cycle time: 28 s → 16 s (reduction 43%)
• Short shots: 4,2% → 0,8% (reduction 81%)

Results after 6 m months:

• Cycle time: 28 s → 16 s (reduction 43%)
• Monthly production: 154,000 → 270,000 s parts (+75%)
• Scrap: 4,2% → 0,8% (savings 81,600 PLN/year in material)
• Energy: Up 12% (new pump), but unit costs -38%

Investment ROI:

• Total cost: 7,500 PLN (maintenance + pump + setup)
• Additional production: 116,000 s parts/month × 0,35 PLN margin = 40,600 PLN/month
• Scrap reduction: 6,800 PLN/month
• Total savings: 47,400 PLN/month = 568,800 PLN/year
• ROI: 7,500 / 47,400 = 0,16 m months = 5 days

Key Takeaways:

• Problems often don't require new equipment - maintenance and parameter optimization suffice
• ΔT > 5°C is an alarm signal - inefficient cooling
• Flow matters more than temperature - turbulent flow ensures effective heat exchange
• Documentation and Tederic profiles speed up optimization for future molds

How to Choose a Cooling System? Decision Tree

Selecting the right injection mold cooling system depends on many factors. The decision tree below will help you make the right choice.

Question 1: What mold temperature is required?

• < 90°C → Water cooling (go to Question 2)
• 90-150°C → Standard oil cooling
• > 150°C → High-temperature oil cooling (synthetic oils)

Question 2: What is the annual production volume?

• < 10,000 s parts → Traditional cooling (drilled channels)
• 10,000-100,000 s parts → Consider conformal cooling for critical parts
• > 100,000 s parts → Conformal cooling economically justified (ROI 12-24 m months)

Question 3: What are the quality requirements?

• Standard (±0,1-0,2 mm) → 6-9 kW water controller, ±3°C precision
• Tight (±0,05 mm) → Controller with PID control, ±1°C precision
• Ultraprecise (±0,02 mm) → Conformal cooling + multipoint monitoring + ±0,5°C controller

Question 4: What is the investment budget?

• Basic (8,000-15,000 PLN) → Single-zone 6 kW water controller
• Medium (15,000-40,000 PLN) → 12 kW oil controller with connectivity
• Advanced (60,000-150,000 PLN) → Multi-channel + conformal cooling inserts

Question 5: What plastic dominates production?

• PP, PE, PS, ABS → Standard water cooling, 6-12 kW controller
• PC, PMMA (transparent) → Water cooling with ±1°C precision
• PA, POM, PBT (engineering) → Oil cooling recommended
• PEEK, PPS, LCP (high-performance) → Synthetic oil cooling required

Recommendation for a typical Polish plant:

• 80% applications: Tederic water controller 9 kW with PID control, 10-90°C range, cost 12,000-18,000 PLN
• 15% applications: Tederic oil controller 12 kW, 90-200°C range, cost 25,000-35,000 PLN
• 5% applications: Conformal cooling for high-volume precision production

Maintenance and Upkeep - Schedule

Proper maintenance of cooling systems ensures process stability and long service life. Neglected maintenance leads to 15-30% cycle time increases and premature component wear.

Daily (5 m min):

• Visualeak check at mold connections
• Verify fluid level in tank (between MIN and MAX)
• Check temperature on display - holding ±2°C
• Pump pressure check - stable 4-6 bar

Weekly (15 m min):

• Cleaning the inlet screen on the temperature controller
• Check quick-connect fittings
• Test HIGH TEMP and LOW LEVEL alarms
• Inspect flexible hoses (cracks, abrasions)

Monthly (1-2 hours):

• Replace or clean mechanical filter cartridge
• Check water pH (7,0-8,5) - out of range risks corrosion
• Mold channeleak test (pressure 6 bar, drop < 0,2 bar/10 m min)
• Verify PT100 sensor accuracy (deviation > 2°C → recalibrate)

Quarterly (4-6 hours):

• Clean plate heat exchanger with citric acid 5%
• Check pump noise level (increase of 10 dB → issue)
• Inspect condition of flexible hoses
• Analyze temperature trends from the last 3 m months

Annually (full overhaul - 1-2 days):

• Complete coolant replacement (water yearly, oil every 2-3 l years)
• Flush mold channels with citric acid 10% for 4-8 hours
• Controller recalibration by authorized service
• Overhaul circulation pump (impeller, seals, bearings)
• Check heating elements (insulation resistance > 2 MΩ)
• Electrical inspection (tighten terminals, thermography, RCD test)

Consumable parts requiring regular replacement:

• Filter cartridges: every 3-6 m months, cost 50-150 PLN
• Quick-connect O-rings: every 3-6 m months, cost 3-8 PLN/pc
• Pump seals: every 3-5 l years, cost 200-600 PLN
• PT100 sensors: every 3-5 l years, cost 150-400 PLN
• Electric heaters: every 5-8 l years, cost 800-2000 PLN
• Flexible hoses: every 3-5 l years, cost 80-200 PLN/m

Annual maintenance cost: 3,000-8,000 PLN per controller (parts + labor), which is 2-5% of the cost of inefficient cooling (200,000-500,000 PLN annually).

Cooling Optimization ROI - Calculations

Optimizing mold cooling is one of the most cost-effective investments in injection molding production. Below are detailed ROI calculations for typical scenarios.

Scenario 1: Maintenance and parameter optimization (minimal cost)

• Investment: 5,000-10,000 PLN (flush channels, replace filters, calibrate, new pump)
• Results: Cycle time reduction of 15-25%, thermal scrap reduction of 40-60%
• Annual savings (at 100,000 s PLN/yr): 80,000-150,000 PLN
• ROI: 1-2 m months

Scenario 2: New temperature controller

• Investment: 12,000-35,000 PLN (water or oil controller Tederic)
• Results: Precision ±1°C vs. ±5°C, process stability, eliminate quality variation
• Annual savings: 50,000-120,000 PLN (scrap reduction + better repeatability)
• ROI: 3-6 m months

Scenario 3: Conformal cooling (strategic investment)

• Investment: 50,000-150,000 PLN (3D-printed insert)
• Results: Cycle time reduction of 30-50%, warpage elimination of 50-80%
• Annual savings (at 200,000 s PLN/yr): 120,000-250,000 PLN
• ROI: 12-24 m months

Comparison with other investments:

• New injection molding machine Tederic: 400,000-800,000 PLN, ROI 3-5 l years
• Cooling optimization: 10,000-50,000 PLN, ROI 1-6 m months
• Cost efficiency: Cooling delivers 10-20x faster ROI at 10x lower investment

ROI Calculation Formula:

• Additional output = (Current output × Cycle time reduction [%]) × Unit margin
• Scrap reduction = Current scrap % × Reduction [%] × Annual output value
• ROI [months] = Investment / (Additional output + Scrap reduction) / 12

Summary and Next Steps

Injection mold cooling is a fundamental part of the molding process, accounting for 60-70% of cycle time and determining part quality. Effective cooling systems are a strategic investment in productivity, quality, and competitiveness.

Key takeaways from the guide:

• 60-70% of cycle time is cooling - the biggest optimization potential
• System types: water (5-90°C, 70% installation), oil (90-300°C), conformal cooling (20-50% cycle time reduction)
• ΔT = 2-4°C is the golden rule - higher values signal inefficiency
• Diagnostics: 85% thermal issues fall into 6 categories with specific fixes
• Case study: Cycle time reduction of 43%, ROI in 5 days, additional 568,800 PLN/yr
• Maintenance: 3,000-8,000 PLN/yr prevents losses of 200,000-500,000 PLN/yr
• Cooling optimization ROI: 1-6 m months (10-20x faster than new injection molding machine)

Next steps:

1. Audit current system - measure temperature at 4-6 points, record ΔT, check flow
2. Identify issues - use diagnostic matrix from this guide
3. Maintenance - flush channels, replace filters, calibrate sensors
4. Parameter optimization - adjust temperature and flow for material
5. Documentation - record optimal parameters for each mold in Tederic system
6. Monitoring - track temperature trends, detect system degradation

If you're planning to optimize your injection molding process or upgrade your machine fleet, contact the TEDESolutions experts. As an authorized Tederic partner, we offer:

• Free cooling system audit (for Tederic customers)
• Selection of temperature controllers tailored to your production needs
• Operator training on optimizing cooling parameters
• Technical support for implementing conformal cooling

Check out our articles on injection molding defects and how to eliminate them, injection molds and precision injection molding, and TCO and energy efficiency of injection molding machines.