Jan 2020 - 07: A New Era of Machine Manufacture

A New Era of Machine Manufacture.
By Kasra Mehraky

Most people don’t pay much attention to the method of construction when looking to purchase a new machine tool.

Although, the most known machine bed structure is gray cast iron and welded steel, there is another
method that has gained popularity, mineral casting.

Whilst there are several methods and materials for producing a machine tool bed, such as polymer concrete, natural or artificial granite, here we will discuss mineral casting technology.
Structural machine tool design continues to go through enormous changes.

One of the more recent technologies for producing machine tool beds is the ‘mineral casting’.

Using this method, the mineral compound is mixed with epoxy resin to make the machine base, guaranteeing maximum rigidity and vibration damping when compared to many established and traditional methods.
Normally, the structure of a machine tool is manufactured from thin steel or iron plate walls that are reinforced with an internal network of plates.

This network is often subjected to extensive trials and testing to yield the most efficient and solid base construction.

But with mineral castings, the machine bed is almost fully filled with a mixture of special epoxxy resin and mineral compounds that turn into a concrete-like material.
There are several ways to produce this kind of machine bed.

The most conventional route is by pouring the material mixture into a mould, made out of wood, plastic or sometimes steel while vibrating it continuously on a surface to reduce the cavities during the casting process.
WHY MINERAL CASTING?
This method of producing machine beds has enormous advantages compared to old fashioned manufacturing processes.

Here's a list of the most significant ones.
Vibration damping: Without doubt mineral casted machines have much greater vibration damping characteristics than traditional casting methods and some companies claim that it is 10 times better than the cast iron bodies.

Of course, vibration damping is a major benefit with regard to the machine tool stability, performance and of course, the quality and precision of the parts machined on the machine tool.
Thermal stability: One of the main issues that concerns machinists and machine tool manufacturers is thermal expansion that occurs when the temperature is increased in the work envelope

This is caused by the machining process and can significantly impact machine tool accuracy.

The mineral cast machine bed has far lower thermal conductivity than a steel bed construction and this ensures the machine produces a consistently high quality and precision level over time.

High resistance to media: Another issue that can reduce the lifespan of a machine tool is material wear that is created due to its contact with oils, coolants and chips.

Compared to other machine manufacturing technologies, mineral cast beds show a promising resistance to material wear over the life cycle of the machine tool.
Integrated bolts, hoses, tubes and power lines: This is very exciting for machine designers.

Mineral cast machine beds can offer designers the opportunity to provide internal lines for different pipes, cables and hoses and this reduces the need for post-cast machining.

This should reduce the labor and subsequent cost of machine tool production.
Super-high precision surface finishes: Mineral cast components can be machined and ground.
To achieve greater flatness and precision, processes such as hand lapping can be implemented on the surface.

Companies such as Hamuel Reikenbahker in Germany offer the total casting and machining service to a wide variety of machine tool manufacturers.
No need for heat treatment: For achieving the best stress-relieving properties, cast iron elements need to be stored for a prolonged period.

The process is known as aged stress relieving.

The shorter route is via a heat treatment process that is costly and has a lot of disadvantages, but with mineral technology, the need for stress relief is generally not required.
In-house production: Many machine builders outsource the casting productionprocess, as it’s difficult and expensive to manage.

Just consider the need for a large iron casting oven and the mould production process.

With the Rampf Group and its EPUMoNT technology, machine builders can just buy the equipment and do it themselves.

This enables machine tool builders to carefully manage the whole process of casting.
As this list shows, the benefits of mineral casting are numerous, and at this point in time, this technology indeed costs more than traditional casting methods.

However, as more machine builders adopt the mineral compound strategy, the price of the components will reduce, as is the case with mass production environments.