What Potential Does Additive Manufacturing Hold for Custom-Made, Complex-Shape Heating Platens?

Compromise machined optimisation printed
A heating platen with complicated interior coolant channels is often made with drilling and filling of many straight holes to make a zigzag path which is more of a compromise than an optimisation. Additive manufacturing has the ability to make the platen with smooth, curving channels that follow the patterns of heat flow more precisely, like arteries in an organ, rather than a rigid drilled network.

This move reflects a significant change in the way thermal tooling is thought about, in that it is the manufacturing methods that are employed to match the thermal design intent, rather than changing the geometry to fit the manufacturing restrictions.

Additive Manufacturing as a Facilitator for Thermal Design Freedom
Custom heating platen technique in additive manufacturing is often based on selective laser melting (SLM) or directed energy deposition (DED). Additive manufacturing manufactures metal components layer by layer from powder or wire feedstock. Processing of materials such as aluminium alloys and tool steels into fully dense structures of complex interior geometry is possible.

In this context heating platens can be constructed with:

Heating element conformal channels following complicated surface shapes

Thermal gradient-aligned, curved interior cooling channels

Integrated sensor channels for embedded temperature measurements;

Internal structures optimised for weight reduction using lattices or topology

This results in a platen that is no longer thermally limited by the constraints of straight line milling.

Think of a platen where the heater is moulded to fit around a complex 3D cavity like a glove, applying heat precisely where it is needed and keeping thermal mass to a minimum.

Control of geometry for enhancement of thermal performance
Additive manufacturing allows for the interior channels to be matched to the areas of heat demand, providing a more uniform temperature distribution over the platen surface. The thermal dead zones usual in traditionally drilled designs can be minimised substantially.

Key effects on performance are:

Optimised positioning of heat sources for shorter heat-up periods

Reduced cooling time by conformal fluid channels

Better surface temperature homogeneity for high precision processes

Less overall mass with internal lattice reinforcing structures

These advancements immediately effect cycle time and energy economy in thermoforming, composite pressing and precision forming applications.

Current adoption and restrictions in industry
Metal additive manufacturing (SLM) has advanced to the point that it is capable of producing fully dense functional components. But there are still some practical limitations:

Post-build heat treatment is needed for residual stress relief

Sealing surfaces and fluid passages often require surface finishing

Production cost is still greater than common machining for simple designs.

Despite these restrictions additive technologies are being used to build prototype platens and low volume production equipment. "The ability to make geometries that you can't drill or mill is a key driver for adoption in advanced thermal systems.

Implications for design and engineering workflow
Additive manufacturing changes the design of the platen from a manufacturing-driven process to a simulation-driven process. In digital space you may iterate the internal channel shape very quickly before printing it out. So thermal finite element analysis becomes key.

This allows:

Rapid prototyping of thermal profiles

Pre-production heating and cooling balance optimisation

Integration of multifunctional properties into a single printed component

The outcome is tighter integration of thermal engineering and mechanical design.

Abstract
Additive manufacturing opens up a new dimension of freedom for the design of heating platens, giving the opportunity to adapt the thermal performance accurately, and allows for the creation of complicated internal geometries, which are not possible with conventional machining.

As printing technologies are advancing, thermal tooling is moving more and more towards digitally designed, function-optimized components. Indeed, machining skill is not the only thing that defines the future of heating platens. Additive manufacturing processes allow the shaping of thermal systems with unprecedented precision.