Even minimal amounts of corrosion and pitting, if neglected, can cause malfunctions or total equipment failure. Even corrosion-resistant materials such as stainless steel are not immune to stains and oxide when exposed to certain circumstances.

What causes oxidation and corrosion of molds?

· Presence of atmospheric moisture, condensation, vapor residues, trapped moisture
· Use of gaseous resins that generate corrosive acid vapors (hydrochloric and hydrobromic acids)
· Use of resins containing halogenated flame retardant additives
· Use of wood fiber and bioplastic loaded compounds that generate excessive residues
· Use of resins with high process temperatures and high injection pressures
· Use of compounds with highly abrasive fills

Molds must be protected against corrosion and oxidation with specific products based on the production scenario. The choice of the correct protector depends on many factors, first and foremost the duration of the necessary protection, the finish of the mold, the type of corrosion to which the mold is exposed, the temperature of the surface to be protected, the production area, and any transportation of the mold, perhaps internationally and with different climatic conditions.

RUST AND ANTI-CORROSION PROTECTORS

HOW LONG DO YOU INTEND TO KEEP THE MOLD?

Short-term protection (one night or one weekend):

In general we recommend once the machine is stopped to always apply an anti-rust product to the mold cavity and plates. The type of protector indicated varies depending on the situation:

1) Non-corrosive plastics and cooled molds:
In these cases the threat is atmospheric corrosion, mainly condensation. At the end of production we recommend first to close the cooling of the mold; then, spray a good spray cleaner with immediate evaporation that does not require manual cleaning and once completely dry give a spray of dry protector, after which close the mold. It is important to do this before water vapor in the air begins to condense.

In case condensation has already formed and water droplets are visible in the surface of the mold then dry the mold completely with a jet of air before spraying the protective film otherwise condensation is trapped between the mold and the protective film with inevitable rust formation. With this sequence that takes a couple of minutes, the mold is effectively protected from condensation that is generated during heating of the mold which can lead to the formation of oxide and rust. The advantage of using a dry protector is that you can restart production quickly without having to wash the mold to remove the protector.

2) Plastics that develop corrosive gases (acetates, PVC, halogenated)
With such gaseous resins the threat is chemical corrosion generated by corrosive acid gases emitted by the plastic material during molding. At the end of production, the first thing to do is always a powerful spray with a valid spray cleaner, assisted by a vigorous wipe with a cloth. Flame retardants contain extremely aggressive halogenated additives, it is essential to remove them before applying the protective agent otherwise they are sealed under the protective layer and corrode the mold. If the mold is heated (50°-100°C) a cleaner with a strong controlled evaporation chemistry should be used. Once cleaning is complete, proceed with the mold protection. In these cases, it is essential to use a protective coating with a specific dual-action formulation, that is, to prevent rust formation and neutralize the action of the corrosive acidic fumes that have impregnated the printer surface. If the mold is hot, the rustproof product protects the mold as it cools. If the heat is extreme, it can cause the oils contained in the rustproof product to liquefy and drip. However, it still provides an important level of protection until the next production start. This procedure is always indicated with hot molds even in cases of long production or mold storage stops because it allows the mold to be protected until the mold is cold enough to be manipulated. This is a so-called intermediate step between the production stop and the mold cleaning restart or activity suitable for thoroughly removing contaminants accumulated on the mold unit during the production cycle before storage.

Long-term protection (months or years):
In these cases the mould must first be thoroughly cleaned and subsequently protected. Applying the protector without first thoroughly cleaning the mold is a useless and worsening operation because it creates a

water-repellent film over a layer of contamination of various kinds in contact with the steel which may affect the undisturbed steel and cause major damage.

1. Storage of the mould within the holding
In these cases, use a protector suitable for the period of time the mold will remain in storage. There are long-term anti-rust products that are effective for up to five years of indoor storage. In these cases, for greater safety, we always recommend using a dual-action protective agent containing inhibitors to atmospheric corrosion and also acid chemistry.

2. Protection of a mould which is to be transported
Molds shipped abroad by truck often stop in very different climatic conditions and experience temperature changes that put the steel to the test. The same applies to sea transport which exposes molds to a highly corrosive environment due to the presence of sea salt, moisture and salt spray which accelerate the degradation of metallic materials. Effective prevention requires the use of specific protectants and packaging. The protector must be specially formulated to ensure effective protection against the threats listed above, and we recommend a protector with an additional colored tint to ensure complete and uniform coverage on all mold surfaces and avoid leaving exposed areas.

Protection of a mold with a mirror finish
Mirror-polished molds are particularly delicate because the presence of oxidation stains may require polishing the surface. It is essential to effectively protect them with a self-cleaning dry protector that requires little or no contact with cleaning cloths. A self-cleaning anti-rust product usually fades when production starts after a couple of molding cycles or can be easily removed with a fast-evaporating mold cleaner.

Protection of a medical sector mold
You are printing parts that will be released into the medical or food market and will only need to consider a formulation certified for these areas.