Cooling time in moulds processing takes one of the highest time and directly impact on overall efficiency of the mould. Since the emergence of Conformal Cooling the Mould Designer & Mold Flow Engineer will have flexible ways to design cooling channel. This solution provides opportunity for Mould Designer to think without limiting of hereditary way of manufacturing cooling channels. Read on to know the fundamentals of conformal cooling, its bene fits and how it is better option then the conventional ones.

 Image courtesy: “EOS GmbH

Conformal cooling is nothing but a cooling walkway which follows the shape of produced part (inside core or cavity of mould) to provide rapid and uniform cooling or sometimes even maintaining the temperature. While designing a mould/ die /insert, design engineer has to pay maximum attention to the temperature management. This temperature management is typically done by designing the mould in such a way that the material flow is quick, uniform and having optimal thickness.

Despite of design engineers best efforts this thermal management is not optimal. In other words the difference between the temperature at the inlet (of mould) and the temperature at the part filled last is high. This normally happens due to the part being intrinsic shapes, Cavity Layouts, Mechanism within moulds occupy more space resulting with limitation to design uniform cooling lines, which finally leads to higher cycle time, higher rejection rates, impact on mould life.

Conventional cooling lines have the limitation of the drilling process and these lines are typically straight channels within the mould. These cooling lines will not always effectively cool the mould as in case of difficult areas will tend to take more time to cool. This thus results to all the mentioned problems. 

Conformal cooling channels on the other hand overcomes this large limitation. Conformal channels snake through the mould in a way such that they are within an optimal distance from the cavity / core / insert / part surface.

This helps the designer to manage the temperature of the mould, and give better results prior to actual manufacturing of the mould.

How conformal cooling works?

Conformal cooling works like a water jacket (in engine) around the cavity / core / insert which makes the shape of part / product helping the mould to cool in optimal time i.e neither quick nor slow.

Cooling channels are created around the profile of part at the best distance to provide best temperature difference in the mould. This in turns reduces the cooling time in the overall cycle time and reduces in process rejection.

Game changer in the tooling industry

While designing a mould, design engineer thinks from manufacturing point of view. Which means he thinks and answers from what can be made, instead of what is needed. Conformal cooling which is typically possible only through 3D printing / Direct Metal Laser Sintering (DMLS) technology gives a upper hand due to advantages like:

Flexibility in design: Conformal cooling channels are typically 3D printed, which makes it possible for cooling to reach the remotest corners of the mould. With conformal cooling, complex parts can be designed and realised. 

Cycle time reduction: In most cases, conformal cooling can be designed to drastically reduce cycle time which is the single largest profitability parameter in injection moulding. In a setting where a mould goes through say 10 lakh shots, reduction of 30% cycle time means your moulding machines will be in operation for 30% lesser time, directly impacting bottom-line

  • Fast to manufacture: The additive approach to manufacturing of such channels and inserts within a mould helps in realising the end result in just a matter of days, as opposed to weeks / months in a conventional setup 
  • Re-work: In most cases, conformal designs are simulated for flow, temperature uniformity and pressure uniformity. Only after the simulation yields satisfactory results, the part is 3D printed. This reduces the need for a trial and error approach which can be time consuming
  • Part Defect & Mould life: Impacts on both these counts are positive, and high quality parts are achieved

Benefits over conventional cooling methods

Conventional cooling channels are typically drilled into the moulds, and as is with the drilling process, only straight holes can be made. This is inefficient in some cases as the cavities are rarely linear and desired cooling does not reach all areas of the cavity.

Conventional channels are designed typically after the design of the mould cavity takes place, and there is very little scope for modifying entry and exit points for the coolant channels within the mould. Clearly, the cavity design takes precedence over the cooling channel design.

This freedom of design is a key element in facilitating rapid and uniform cooling across the cavity. This directly impacts the cooling time which is a bulk of the cycle time in the injection moulding process.

Cases have been demonstrated where cooling times have been reduced by a staggering 50-70%. Besides cycle time, proper thermal management facilitated by the conformal nature of cooling drastically reduces defect rate, which also yields positive dividends to clients.

Importance of engineering analysisz

Simulation helps in comparison of existing and improved conditions with conformal design with the forecasted results in terms of quality, cooling time reduction, overall cycle time.

As simulation gives a predictive outcome, any design modi¬fications can be made, either to the cavity or the cooling channels before moulds are put to production. Overall, this helps in delivering moulds to clients faster. 

Additive manufacturing and Conformal cooling

Without a doubt, Additive manufacturing has the potential to massively impact the tooling industry. With DMLS, you start with a thin metal powder layer.

Essentially the mould design is broken down into many segments and each segment is a layer of powder to begin with. This layer of powder is selectively sintered using a powerful laser, thereby solidifying only the required area. Then a new layer is applied over the previous layer, and the process repeats.

Also with new benefits like Layer Segmentation where different layer thicknesses can be used depending on internal intricacies, Hybrid Manufacturing where one can combine conventional manufacturing with DMLS to make perfect use of AM and many other notable inventions are opening new opportunities. Additive manufacturing makes it possible to realise parts which have very intricate and challenging internal features such as conformal channels. The extra effort in design is worth it as Additive manufacturing in itself takes very little time instead of Subtractive (conventional) manufacturing / material removal. The end results in most cases have significant cost and longevity benefits to our clients.

Going forward

The industry will shift towards this technology as it helps to drastically improve e fficiencies. There will be a learning curve. As the design method is quite diff erent to what engineers are currently used to, some skilling is required for design and simulation.

Using DMLS for conformal design of moulds / inserts is certainly here to stay, and we expect larger number of OEMs to adapt this feature within their moulds.

About Author:

Guruprasad Puranmath is the Head of Tool Room at Mutual Engineering Pvt ltd. With about 15 years of experience, his experience counts from strong base of Design & Manufacturing with updated technology.