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We have listed below
the most important and frequently
asked questions
raised by visitors
to the TTI website with the appropriate
answers.
How to classify and determine properties of steel (Mold Material)
COMPARISION OF TOOL STEEL W.R.T TEXTURABILITY,POLISHABILITY AND WELDABILITY
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Not Suitable
-+
Critical
+
Suitable
++
Well Suited
+++
optimal (High Gloss)
The quality of steel determines to a great extent the quality of texuring.A high degree of purity with
respect to the levels of oxide and sulphur,a uniform and fine micro-structure as well as low levels
of segregation result in uniformity in texturing.The quality of the texture is primarily determined by
the quality of the machined surface.Repaired welded areas or residual material from erosion can
impair marked surface.
Why is anti-squeak necessary?
When twoplastic parts come in contact and rub against each other they produce a squeaking noise
which is undesirable. In order to avoid this squeaking noise the concept of anti-squeak grains has
been conceived. Anti-squeak grains are nothing but certain types of technical or spray grains with
their depths reduced (about 50%).Reduction of depth results in less area of contact between the
parts. Selection of textures for anti-squeak parts involves analysis of the design of the textures,
surface area and the depth.
Please contact your nearest T.T.I partner for advice.
What is the major cause of scratch on a plastic parts after the etching processes?
You may simply think that the uneven surface of grain may result in the scratches. However, it is
actually more dependent on the shape of the plastic product and the type of resin utilized.
When you put grains on the inner surface of a cup, the heavier contraction to the direction of the
center of circle or to the inner area results in the tight touch between the product and mold avity.
In this case, risk of scrach increases, of course. On the other hand, resin with a large coefficient
of contraction such as PP is used for bigger sized products such as instrument panels or floor
consoles, scratches can occur even on the flat surface irrespective of the grain type and its depth.
Other factors like thickness of the plastics and draft angle also influence scratches and are
necessary to be controlled by adjusting the pattern shape, orientations, draft angle, etc.
Why is gloss important?
Gloss is the measure, or perception, of light reflection from the surface of a part. Gloss is of
particular concern on textured plastic parts because of perceived quality and realism.
Low gloss is often desired to make a leather grain look realistic. Gloss can also be a safety
concern due to glare reflected in the windshield of a vehicle. Gloss can be controlled on the tool
surface by either a dry blast application with a media of oxide and glass, or by an actual "micro"
texture applied to the tool surface. Tool surface is only one component of a low gloss part.
Molding parameters, tool configuration, and plastic material also significantly affect gloss.
What is the effect of EDM (Electric Discharge Machine) in etching processes?
EDM is one of the widely used methods in the construction of steel mold cavities.
Sometimes application of the characteristic EDM patterns is directly used in generating grains,
but it has to be done with great care and thorough preliminary examination is necessary
depending on the art size and its shape.
In general, EDM produces a hardened surface of steel. In order to have better result of etching,
you may need to remove this layer by polishing the surface to obtain a uniform roughness and
hardeness prior to etching processes.
Degree of polishing can be determined by the type of pattern grains which should be advised by
our specialists.
