General corrosion and scale workpiece temperature should be selected pickling, can only be assured within 10min completely remove rust, and scale. Unless there is sufficient reason, generally do not choose low or no heating pickling rust, only cold pickling such as: the workpiece rust rarely, non-oxide; rust unlimited time; allow the use of hydrochloric acid and so on.
Surface conditioning step, generally without heating, is generally processed at room temperature.
Or low temperature phosphating, phosphating fast no significant difference in a short period of time can be quickly formed phosphate film. Workpiece phosphide after, if required storage time between long step change should select temperature phosphating, it will have a better anti-corrosion effect.
Throughout the pre-treatment process, can be employed at room temperature without heating wash mode, if the last one is the hot water washing dry, the water temperature should be above 80 ℃.
3 Processing time
Treatment, treatment temperature Once selected, the processing time should be based on the work of the oil, the extent of corrosion to be. General can refer to the instruction manual processing agent processing time requirements.
Process 4
According to the workpiece oil, rust and primer degree requirements, divided into different processes.
4.1 is completely rust-free workpiece
Pre skimmed - degreasing - water washing - Table tune - phosphide - water washing - drying (electrophoretic paint drying time to time, directly into the electrophoresis tank). This is a standard four-station process, wide range of applications, suitable for all kinds of cold-rolled plate before and rust workpiece machining process, it can also be added to the table transfers degreasing tank, reducing a surface conditioning step.
4.2 General grease, rust, scale mixed workpiece
Degreasing rust "Combo" - water cleaning - and - Table tune - phosphide - water washing - drying (direct or electrophoresis). This process is the most widely used processes, pre-treatment for all types of work (heavy oil excluded); if temperature phosphating, surface conditioning step may also be omitted, a simple plate of the workpiece, and can also be saved in step process to become four-position standard rusted parts.
4.3 Heavy oil, rust, scale workpieces
Pre-degreasing - water washing - degreasing rust "Combo" - water cleaning - and - Table tune - phosphide - water washing - drying (or directly into the electrophoresis tank). For heavy oil workpieces, first pre-degreasing, to remove most of the fat, in order to ensure that the next step after degreasing rust "Combo" to give completely clean metal surfaces.
5 Some Notes
In the process of designing some very small places should note that even with some design-related equipment, if ill-considered, the operation will generate a lot of negative impact on the operation and production line workers, such as a step interval, overflow water, phosphorus of slag, craft hole in the workpiece, tank and heating materials.
5.1 step intervals
The interval between each step, if too long, it will cause the workpiece during operation of secondary rust, especially when the pickling process, after pickling the workpiece in the air easily oxidized rusty pan-green, with a best step between the protection of water film can reduce rust. Rusty yellowing pan-green parts, seriously affected the phosphate effect, causing the workpiece hanging gray, yellow, can not form a complete phosphate coating, it should be possible to shorten the interval between processes. If the interval between the step is too short, water, water in the work place can not be completely effective drain, resulting in channeling phenomenon, especially when the spray pattern will produce mutual splash spray string groove, so difficult to control the bath composition, bath even destroyed. Therefore, in considering the step interval should be based on the workpiece geometry, shape, choose an appropriate step interval.
Promote water overflow, in order to ensure that the workpiece sufficiently cleaned, reducing channeling phenomenon. When should overflow from the bottom of the water, the upper part of the diagonal open overflow hole overflow.
5.3 Process workpiece hole
For some dead water in the tubular member or workpiece is easy to form, you must select the appropriate location drilled hole technology, to ensure adequate water flow to do in a short period of time. Otherwise it will cause channeling or to drain a long time in the air, secondary rust, phosphide affect results.
Phosphate Cleaner 5.4
For any kind of phosphate solution will produce more or less sediment (LRT System Phosphating sediment rarely), the process should be designed to indicate when the device has a phosphate slag, especially when spraying phosphide, Cleaner means essential, typical cleaning plant are: the inclined plate settler, high sedimentation tank, centrifugal cleaners, paper bag residues so choose.
5.5 tank and heating materials
While tank heating pipe material selection process design is not the content, if not reminded in the process design, equipment design may cause negligent staff, and affect the operation of the entire production line. For sulfuric acid, hydrochloric acid when its tank material, use only glass, steel, granite, plastic, heating pipes only use lead-antimony alloy tube, ceramic tube, not made of stainless steel materials. If the use of phosphoric acid, the tank and the heating pipe materials can be made of stainless steel material, of course, glass, steel, plastic, granite can be.