First Shot Samples Polished before the Buyer Ever Sees Them
Doctored T1 samples hide draft and thermal flaws through hand polishing; enforce raw steel T0 audits with continuous cavity telemetry before sign-off.
VDI 3400 Spark Erosion Scales
Meaning
Reference scales categorize the surface roughness produced by electrical discharge machining on the metal surfaces of a mold tool. The vdi 3400 spark erosion scales provide a standardized way for toolmakers to define the texture of a cavity, especially when a non-polished, matte finish is required. This system is widely used in Europe and is increasingly common in global sourcing because of its precision and ease of measurement.
Texture Specification
Scale consists of thirty discrete steps, with higher numbers indicating a rougher surface with deeper pits and peaks. Each step corresponds to a specific arithmetic mean roughness value, allowing the designer to choose a texture that meets both functional and aesthetic needs. These textures are created by the sparks of the EDM process, which melt and remove small amounts of steel to leave behind a uniform pattern that is replicated on every part.
Functional Consequence
Roughness of the mold surface affects how the part releases from the tool and how it feels in the hand of the user. A textured surface can help to hide defects like sink marks or weld lines, but it also increases the friction between the part and the mold during ejection. Engineers must ensure that the mold has enough draft to allow the textured part to slide out without scratching or sticking.
Measurement Limit
Visual comparison plaques are often used on the shop floor to verify that the mold finish matches the specified VDI level. While these plaques are useful for a quick check, an accurate measurement requires the use of a profilometer to determine the actual roughness of the steel. The scale is most effective for defining the primary texture of the mold and is not intended to describe the subtle variations caused by the moulding process itself.