In the last few years, many companies in the USA have
adopted stainless material almost exclusively for the manufacture of mould bases. Do our
American friends know something we don't?
Traditionally, stainless mould base and core and cavity steels have been
specified whenever there was a risk of corrosion from acid evolving polymers such as PVC.
However, there are also sound economic reasons for using stainless when moulding more
benign materials or when moulding in humid atmospheres. These are:
Mould bases remain corrosion free during storage either as pre-machined
blanks or as finished moulds or mould components.
No special measures such as plating are required to keep water-cooling
channels corrosion free for maximum cooling efficiency.
Stainless mould bases have become a standard for most clean room moulding
environments, necessary for the production of critical plastic parts for applications
including medical, food, beverage, packaging etc. No corrosion/ rusting or deterioration
of moulds can be tolerated in these moulding conditions, tools need to remain in pristine
condition throughout their life.
Repairs and modifications by welding are straightforward providing that a
suitable mould base material and filler are selected.
Several of the available alloys are formulated to be free machining.
Lower mould maintenance costs exist over the entire life of the tool
During the last 25 years, DIN 1.2085 / 420-type stainless steels have been
increasingly used and specified in the construction of high cavitation plastic mould
tooling. Today the change to stainless continues with many companies building 100% of
their moulds from stainless. However, DIN 1.2085 / 420F modified stainless steels possess
inherent negative features. They are characterized by poor weldability, inconsistent
microstructure, varying mechanical properties; hardness variations from plate to plate and
poor thermal conductivity.
These shortcomings have been overcome in a brand new stainless mould steel
now available from Carrs Tool Steels known as RoyAlloy (patent pending). This steel, the
result of an extensive five year research programme by Edro Specialty Steels Inc., is a
superior "new generation" 400 series martensitic stainless holder steel supplied
pre-hardened to 32-36 HRC.
RoyAlloy is characterized by, and has been specifically designed to offer,
improved ductility, increased toughness, better impact strength, safe and simple
weldability and enhanced machinability compared to the existing traditional 420F modified
stainless holder steels available today. RoyAlloy does not exhibit any negative
characteristic compared to DIN 1.2085 / 420F steels.
RoyAlloy is rapidly becoming accepted by leading manufacturers of
high-volume stainless mould tooling and producers of both standard and custom mould bases
as an improved and superior stainless mould base steel.
Users of RoyAlloy, include a diverse range of mould makers, mould base
manufacturers and plastic moulders producing plastic parts for various industries
including medical, packaging, food, beverage, automotive, electrical and electronics. |
