Thermal oil plays a critical role in the heating system of Huibo Machinery’s short-cycle hot press machines. It ensures fast heating, stable temperature distribution, reduced energy consumption, and consistent surface quality during melamine lamination. Using the correct thermal oil and following proper maintenance procedures will significantly improve equipment performance and service life.

This guide is developed by Huibo Machinery’s technical engineering team based on extensive industry experience.

1. The Role of Thermal Oil in Short-Cycle Hot Press Machines

Precise Heat Transfer
Ensures uniform temperature across the upper and lower platens for stable curing and consistent color on the board surface.

Higher Lamination Quality
Reduces issues such as uneven gloss, under-curing, and surface spots.

Extended Equipment Lifetime
High-quality thermal oil minimizes carbonization, pipe blockages, and pump wear.

Better Energy Efficiency
Oils with good fluidity improve heat transfer efficiency and reduce operating costs.

2. Recommended Thermal Oil Selection for Huibo Short-Cycle Presses

Short-cycle presses operate under frequent start-stop cycles, high temperature, and rapid heating requirements, so Huibo Machinery recommends the following:

2.1 Type of Thermal Oil — Prefer “Fully Synthetic”

✔ Excellent thermal stability
✔ Lower oxidation rate
✔ Longer service life
✔ Suitable for continuous high-temperature operation

Mineral oil is not recommended for short-cycle high-intensity production.

2.2 Working Temperature Requirements

Typical operating temperature for Huibo presses:
180–230°C

Recommended thermal oil specification:
✔ Maximum operating temperature ≥ 300°C
✔ Applies to 300-grade synthetic oils or equivalent

2.3 Key Technical Indicators to Check

Commonly used brands in Huibo projects:

Sinopec 300 series

Mobiltherm 600 series

Therminol synthetic oils

Kunlun L-QB 300 series

3. Proper Use of Thermal Oil

3.1 Initial Heating Procedure After Filling New Oil

To protect the platen and pipeline inside a Huibo press, follow these steps:

50–80°C → Hold for 20–30 minutes (remove moisture & air)

120–150°C → Hold for 15 minutes

150–180°C → Raise gradually

Reach operating temperature slowly → Begin production

Never heat directly above 180°C in one step.

3.2 Maintain a Sealed System

The Huibo thermal oil system is designed as a semi-closed circulation loop:

✔ Expansion tank must remain oil-sealed
✔ Avoid air entering the system
✔ Oil level must stay within the safe range

Air accelerates oxidation, leading to darkened oil and carbon buildup.

3.3 Normal Operating Pressure

Pressure should increase gradually with temperature. Abnormal signs:

Rising pressure → possible blockage or degraded oil

Dropping pressure → possible leakage or pump wear

4. Routine Maintenance & Inspection Schedule

4.1 Daily Checks

Leak inspection at joints and valves

Pump running conditions (noise, vibration)

Temperature and pressure stability

Platen temperature uniformity

4.2 Monthly Checks

Visual inspection of oil color

Clean oil filters

Check expansion tank oil level

Check pump seals and pipelines

4.3 Oil Quality Test Every 6 Months

Send samples for analysis. Key indicators:

✔ Acid value
✔ Viscosity change
✔ Flash point
✔ Carbon residue
✔ Low-boiling content

Replace oil when AV > 0.5 mgKOH/g or viscosity increases > 20%.

5. Recommended Oil Replacement Cycle (Huibo Standard)

Based on long-term production data and field service experience:

Normal production:

Every 1.5–2 years

High-intensity 24h production:

Every 1 year

Replace early if the following occurs:

Oil becomes dark or contains sediment

Heating speed decreases

Large temperature difference between platens

Pump load increases

Test results exceed acceptable limits

6. Thermal Oil Replacement Procedure (Simplified)

Stop the machine and cool to below 60°C

Open the drain valve and remove all old oil

If carbon buildup is heavy → circulate cleaning oil

Refill with new thermal oil

Run circulation pump to remove air

Follow initial heating procedure

Record replacement date and operating parameters

7. Huibo Machinery Engineering Recommendations

Use the same brand of oil to avoid chemical incompatibility

Do not mix synthetic and mineral oils

If the press will be idle long-term → keep the system filled to minimize oxidation

Never exceed the oil’s maximum temperature rating

Proper use and maintenance of thermal oil ensures stable temperature control and maximizes the performance of Huibo short-cycle hot press machines.