Cold Formed Steel Step Pin with Flat Slot for Automotive Mechanism Control

Product Description:

The Qimao Metal Manufacturer produce Cold Formed Steel Step Pin with Flat Slot for Automotive Mechanism Control by SCM435 or customized wire rod. Goes into a multi-station cold former – the machine upsets the material into two distinct step diameters in one hit. No turning, no grinding on the steps. The grain flow bends around the contours instead of getting cut through, which makes a difference when the fork repeatedly strikes the shoulder under load.

After forming, they’re batch loaded into a continuous furnace. Carburizing atmosphere, hold temperature, oil quench, then temper back to get that 58-62 HRC range. We don’t go harder because you lose impact resistance. The flat slot gets broached in a secondary operation – width and depth held to within a couple hundredths. Phosphate coating goes on last. It’s a thin layer, maybe 0.01mm, but it holds oil and prevents scuffing during the initial run-in period.

Specification:

Products Details:

Four step diameters on this Cold Formed Steel Step Pin with Flat Slot for Automotive Mechanism Control. The larger shoulder is the one that takes the beating from the shift fork. That’s where the load lands when the driver moves the lever. The smaller diameter acts as a pilot through the selector rail. Between them, you’ve got a radiused transition – avoids stress concentration where the fork impacts.

The flat slot runs parallel to the pin axis. Depth is around 4mm, width matches the fork tine thickness with about 0.1mm clearance. Not too tight, not sloppy. The phosphate coating is manganese-based, gives the surface a slightly porous finish that holds residual oil. Hardness we test on every batch – Rockwell C scale, usually lands around 60 HRC nominal. Case depth about 0.8 to 1.0mm. Core stays tougher at around 35 HRC. That’s the thing with SCM435 – you get a hard shell and a ductile core, so the pin doesn’t snap when the fork slams into it.

Product Feature:

• Four step diameters with a radiused fillet between them. The radius is critical – eliminates the sharp corner that would otherwise start a crack under cyclic loading.
• Flat slot broached to a controlled width. We use a pull broach, one pass, so the slot walls come out square to the pin axis. Fork slides in without binding or excessive play.
• Phosphate coating is manganese-based. It’s not just for corrosion – the porosity holds lubricant, reduces friction during the first few thousand shift cycles.
• Hardness gradient. Surface at 58-62 HRC, core around 35 HRC. The case is thick enough to handle wear, but the core stays flexible enough to absorb shock loads.b

Product Application:

• Cold Formed Steel Step Pin with Flat Slot for Automotive Mechanism Control for Manual transmission shift towers – the slot engages with the fork tine, translates driver input into selector movement.
• Automated manual transmissions – same concept, but actuated by electro-hydraulic shift actuators.
• Some transfer case applications – we’ve supplied similar pins for 4WD engagement forks.