Processing powder coating

Victrex PEEK is available in different viscosity grades suitable for extrusion processes, powder coating and compression moulding. PEEK 150P (Mw -40000 g/mol, d2.oc = 1.32 g/cm3, Tg = 147°C, Tm = 345°C), a coarse powder, presents the lowest viscosity grade and is the most suitable for potential aircraft applications. 

To prevent rejects, retouching and to reduce cost of conservatively more than enough applied powder in powder coating processes a handy measurement system allowing to determine the... 

Of our special interest is the thickness measurement of powder coatings. While the sound velocity of the electrostatic applied powder/air mixture is estimated to be two times the velocity in air it is also an estimation that thickness powder / air layer is reduced by a factor of 5 by smelting (burning in process, hardening). 

The required resolution for the powder coating thickness measurement problem is about 5 microns. Therefore a processing time unit of 0.08 ps (12.5 MHz) seemed to be ok (compare line 2 in table 1). First results based on real measurement are documented in Fig. 7. and are very promising result. Today corresponding patent is pending [7]. 

D. Murphy and G. Tupper, Users Guide to Powder Coating Association for Finishing Processes of the Society of Manufacturing Engineers, Dearborn, Mich., 1985, pp. 33-58. 

The use of nylon-11 for powder coatings or dry coatings (qv) has been developed in response to a growing concern for the environment (44) (see Coating PROCESSES, powder technology). Electrostatic deposition allows thin films to be appHed to metal substrates. Once the powder is appHed, it must be melted and coalesced into a continuous plastic film. Eorced draft or irradiant ovens are used for fusion, and because no polymerization or cross-linkage are required for curing, coated objects can be processed quickly and air-cooled (45). 

Almost all PVC powder coatings are appHed by the fluidized-bed coating process. Although some electrostatic spray-grade formulations are available, they are very erratic in their appHcation characteristics. The resistivity of plasticized PVC powders is low compared to other powder coating materials and the appHed powder quickly loses its electrostatic charge. For the same reason, PVC powders show poor appHcation characteristics in an electrostatic fluidized bed and are seldom used in this process. 

Sherardizing-the process of coating iron or steel with zinc by heating the product to be coated in zinc powder at a temperature below the melting point of zinc. 

Fluidised bed This process is used for powder coating Basically, the equipment consists of a dip tank with a perforated shelf near the bottom. The powder is placed on this shelf and low pressure air is fed under the perforated shelf, resulting in a cloud of fine powder in the body of the dip tank. The article is heated to a little above the melting point of the powder and is then dipped into the fluidised bed for a short period. It is then withdrawn... 

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