- Information about technological processes
and working systems . Everybody can contribute with documentation,
that must be sended to firstname.lastname@example.org
accompanied with the name of the source, and if possible the link
of the site one where there is the possibility of a deepening.
- Surface treatments are applied to castings
for engineering, aesthetic and economic reasons. The surfaces
of industrial castings may be treated to provide improved surface-related
properties such as wear, fatigue and corrosion resistance. In
castings used in consumer products, improved appearance is also
an important objective of surface treatments.
- In many cases, surface treatment permits
a casting to meet mutually exclusive design objectives. For example,
the application of an abrasion-resistant coating will enable a
casting to be both wear resistant, a surface property, and impact
resistant, a bulk property. However, regardless of the engineering
and aesthetic objectives, the main reason for using surface-treated
castings is that they offer the most cost-effective means of meeting
- Surface treatments commonly applied
to castings include: thermal and mechanical hardening treatments:
the application of fused coatings to reduce friction and improve
wear and corrosion resistance; the use of hot dipped metal coatings
to improve appearance and corrosion resistance: the electrodeposition
of metal coatings to increase corrosion and wear resistance and
improve appearance and the application of diffusion coatings to
increase resistance to wear, oxidation, and corrosion.
- Thermal surface hardening is a common
and highly cost-effective method of improving the wear and fatigue
resistance of castings. Thermal hardening involves the rapid heating
of the surface layer of a casting to produce a high carbon austenite
which, upon removal of the heat source, is cooled sufficiently
rapidly, either by self-quenching or the application of a quenching
medium, to produce a martensitic structure. In addition to significantly
increasing hardness, the formation of martensite creates compressive
stresses in the surface layer, impeding the formation and propagation
of cracks. Although slightly softer than hardened steel, the combination
of a martensitic matrix and graphite nodules in surface hardened
can produce superior resistance to sliding wear. Flame, induction,
and laser hardening are the most common methods used to thermally
surface harden castings.
Anodizing - The Optimum Finish for Architectural
Anodizing is an electrochemical process,
unique to aluminum, that increases the thickness of a passive,
naturally occurring, protective aluminum oxide film.
It is the only finish that satisfies each of the factors that
must be considered when selecting a high performance architectural
- Anodizing is a reacted, not an applied
finish that is integrated with the underlying aluminum for total
bonding and unmatched adhesion.
- It is non-selective process and protects
all exposed and unexposed surfaces. An anodized finish is a uniformly
thick, ceramic-like, transparent coating that does not hide defects
or potential problems.
- It is sapphire hard and provides
superior resistance to abrasion and scratching. Scars and wear
from fabrication, handling, installation, graffiti, and frequent
usage are virtually non-existent.
- Harder, smoother surfaces mean less
friction, easier movement, and extended hardware and weather-strip
life in operating components.
- Anodized surfaces, like other adjacent
or surrounding materials, are unaffected by acidic cleaning solutions
or misplaced mortar when properly protected or timely and thoroughly
Electroplated Hard Industrial Chrome
- Typically, wear occurs when hard particles
are present between two surfaces sliding against each other with
intended motion. These hard particles can be either foreign particles
from the environment or metal debris from one or both mating surfaces.
The predominant historical coating to protect against this type
of wear is hard industrial chrome. Electroplated hard industrial
chrome can be applied in various thickness ranges from 0.0001"
up to approximately 0.020" without degradation of the wear
Hard industrial chrome is a porous coating which contains microscopic
fissures due to the way in which chrome is applied to the base
metal. While chrome of 0.005" -0.010" thick will provide
optimum protection against wear, over time, a corrosive environment
will break down the chrome before its typical wear life has been
realized. It does this by attacking the base metal under the chrome
and the subsequent rust causes a break in the adhesion of the
The way to combat this is to apply a thin
layer, less than 0.001" up to 0.002" thick, of Nickel
before applying the chrome. This layer will provide the corrosion
resistance needed to allow the chrome to realize its full wear
Whether we apply Chrome, or Nickel-Chrome,
we can achieve a wide range of surface finishes to meet customer
needs. Typical polish finishes range from 1-2 RMS up to 32 RMS.
Typical matte finishes (blasted or nodular) can range from 30
RMS up to 200 RMS. Lower RMS provides higher friction between
the roller and the material passing over it.
Hot dip galvanizing is a self inspecting
process that relies heavily on proper design to achieve a quality
result. The major difference between hot dip galvanizing and paint
coatings is that hot dip galvanized coatings can only be applied
to perfectly prepared surfaces.
DESIGN MANUAL FOR GALVANIZING
Hot dip galvanizing provides the highest
quality corrosion protection for steel. Understanding the fundamentals
of the galvanizing process and important design factors for steel
products to be galvanized will help you to get the best protection
for steel products. This section describes the galvanizing process
and important design factors. More Information is available in
the Industrial Galvanizers "Design
for Galvanizing Manual" which can be downloaded.