Transformer steel clamp process production

1. Definition of transformer steel clamp terms:
After the skeleton of the winding in the high-frequency transformer is assembled with the magnetic core, the peripheral package of the magnetic core needs to be clamped by a clamp (steel clamp) to play a fixed role, so that it can achieve a stable inductance when the transformer is working, and the steel clamp (circlip) also supports the entire transformer to be welded to the circuit board, and this type of metal clip is called the transformer iron clamp (steel clip, circlip, CLIP).
2. Common materials for transformer steel clamps:
A) Stainless steel (SUS301) B) High carbon steel (SK7) C) Phosphor copper (C5191) Copper (C1100)
3. Common classification of transformer steel clamps:
   RM Series (RM4, RM5, RM6, RM6-C, RM7, RM8, RM8-S, RM9, RM10, RM12, RM14)
   ER Series (ER9.5, 11.5, 13.6, 14.5)
   EF Series (EF20, 12.6, 16, 19, EF20, 25, 30)
   EPC Series (EPC10, EPC13, EPC17, EPC19, EPC25, EPC30)
   EE Series (EE5.0, EE5-1, EE5-2, EE5-3, EE5-4)
   EFD Series (EFD10-1, EFD12-1, EFD15, EFD15-1, EFD17, EFD20, ETD20-1, EFD25, EFD30)
   EFD Double Buckle (EFD15 Double Buckle, EFD20 Double Buckle, EFD25 Double Buckle, EFD30 Double Buckle)
   ETD Series (ETD29,34,39,44,ETD49,54,ETD59)
   FK-ETD （FK-ETD29，FK-ETD34，FK-ETD39，FK-ETD44，FK-ETD49，FK-ETD54，FK-ETD59）
   EP Series (EP5 Cover, EP7 Male and Female Buckle, EP7-1, EP10-5, EP13, EP13-1, EP17)
   PQ Series (PQ2020, PQ4040, PQ5050, PQ3415, PQ3419, QP-20, QP-25)
4. Production process classification:
The first category: stamping and forming------ cleaning----- inspection---- packaging and shipment; (This type is suitable for the production of stainless steel SUS301 material)
The second category: stamping and forming------ heat treatment (hardening), surface tinning----------- inspection, packaging and shipment; (This type is applicable to SK7 material production)
The third category: stamping and forming ------ surface tinning------ inspection and packaging shipment (this kind is applicable to the production of phosphor copper C5191 material)
5. The selection of materials in the stamping process and the difference between the characteristics of each material:
        Under normal circumstances, the transformer iron clamp is mainly matched according to the functional design of the high-frequency transformer when selecting materials in the stamping process; For example, RM series transformer is a new type of ferrite core designed to meet the requirements of modern switching power supply transformer, its core tightly wraps the wire wrap in it, can make the transformer leakage inductance as small as possible, and then clamp the core through the peripheral transformer iron clamp, in this case, to keep the inductance inside the coil in the original state, a clamp with a certain elastic force is needed to clamp the core, if the tape is wound, the expected effect can not be achieved, and the labor time spent by winding the tape is relatively large; At this time, in order to consider the cost and cost performance of iron clamps, we generally choose SK7 as the raw material of iron clamps; SK7 material is a high-carbon steel synthesized with carbon, silicon and manganese elements, which is used after quenching and hardening, and has excellent wear resistance, the hardness before stamping is low at about 13-15HRC, the forming traceability is good, and there is a certain guarantee for the size control during stamping, when the product is stamped and formed, it is quenched to 55-60HRC after vacuum heat treatment, and then tempered to 38-42HRC, at this time, the hardness control is stabilized in this range, if the core is too hard, it is easy to be brittle, and the clamping force cannot meet the requirements if it is too soft; After heat treatment, the surface of the iron clamp is electroplated with tin layer, which is mainly to achieve the solderability of the pin and the anti-rust and anti-oxidation performance of the surface; Therefore, the high-frequency transformer clamps in the industry, such as RM series and EP series, choose to use SK7 for stamping heat treatment and plating.
       Another material is the stainless steel material that we often come into contact with, and the stainless steel material is often concerned about the fact that this material has good resilience, has a certain deformation space during assembly, and can play a better role in fastening; Furthermore, it is optimistic that the anti-rust performance is good, and the surface appearance is relatively bright after assembling with the transformer core coil, so many series of stainless steel materials are widely used in the transformer iron clamp, such as ETD series, EFD series, ER series, UU series, etc.; This material has good anti-rust and anti-oxidation performance, mainly because the material contains different proportions of nickel elements, nickel elements can be formed into nickel oxide in humid air oxygen to prevent further oxidation, nickel has strong acid resistance and corrosion resistance, nickel is also a relatively expensive material, so stainless steel materials are combined into a variety of grades through different types of elements; Common such as SUS201, SUS301, SUS304, SUS316 and other series; Comparisons can also be made with the following ingredient contents:
201 ：C≤0.15 Ni3.5～4.50 Cr16.00～18.00，Mn<=5.5--7.50 Si<=1.0 S<=0.030 P<=0.035
   301： C≤0.15 Ni6.00～8.00 Cr16.00～18.00，Mn<=2.0 Si<=1.0 S<=0.030 P<=0.035
304： C≤0.08 Ni8.00～10.00 Cr18.00～20.00，Mn<=2.0 Si<=1.0 S<=0.030 P<=0.035
316： C≤0.08 Ni10.00～14.00 Cr16.00～18.00，Mo2.00---3.00 Mn<=2.0 Si<=1.0 S<=0.030 P<=0.035
   According to the current market price of materials, the price of 316 grade is more expensive than the other three, and 201 is relatively the cheapest grade; Usually the cost of better stainless steel materials is also relatively high; Therefore, SUS301 is usually used in the selection of transformer steel clamp materials, which can achieve the elasticity required for assembly in terms of performance, and the price is also affordable; In addition, SUS301 and SUS304 have their own advantages in terms of elasticity, SUS304 is more suitable for the production of cyclic rebound parts, while SUS301 focuses on the stability and durability of resilience, so the choice of SUS301 for transformer steel clamp just meets the needs of the core assembly function.
         There is also a transformer steel clamp material is C5191 (phosphor copper) material, which has extraordinary corrosion resistance and high corrosion resistance to dilute sulfuric acid, hydrochloric acid and fatty acids; Therefore, this kind of material belongs to a grade of copper series, so copper is widely used in many electronic and electrical industries in our company, but the cost of the material is also relatively high compared to other materials; C5191 phosphor copper is a synthetic material with copper, tin and phosphorus as the main elements, because the addition of tin elements effectively improves the good performance of oxidation resistance and welding, phosphor copper has good elasticity compared with other copper materials, and has good heat dissipation performance of phosphor copper materials, so it is suitable for all kinds of buckle clips, bullet clip parts production, generally C5191 material is used in the use of transformer iron clamps, or some well-known enterprises have higher requirements for the stability of product performance products; Such as PQ series iron clamps, EE5 inductance transformer series copper guide (clips) to be welded, etc.