Ironing for solenoid valve housings: DT4E pure iron and DC04

The solenoid valve housing is the part where ironing earns its place most clearly. It has to do several things at once: guide the armature in a bore that is round and consistent along its length, fit the coil and the valve body on the outside, stay thin enough that the magnetic circuit works, and do it without surface damage that would disturb the magnetic path.

Balford forms these housings from DT4E electrolytic pure iron and DC04, using deep drawing followed by ironing, with magnetic annealing after forming.

Why the housing is the classic ironing application

Both diameters are functional. The bore is the armature guide; the outside diameter locates the housing in the coil and the valve body. Both carry tolerances, so both have to be formed or turned.
The wall is thin. A thin wall is what makes the magnetic circuit efficient, and it is also what makes the part impossible to produce economically by turning from bar.
Surface damage matters. A scored or torn bore surface is not only a fit problem - on a soft-magnetic part it is also a magnetic path problem. Ironing burnishes rather than tears.
The wall has to be uniform. Uneven wall thickness means uneven magnetic behaviour around the circumference, and it means the armature guide is not concentric with the outside.

Material notes

Material	Why it is used	What changes in the ironing process
DT4E electrolytic pure iron	Soft magnetic: low coercivity, high permeability. Used where the housing is part of the magnetic circuit and the magnetics are specified	Ironing thins the wall without the surface damage that would raise coercivity; magnetic annealing after forming sets the magnetic properties and relieves the cold work
DC04	Deep drawing grade steel: high formability, consistent thickness. Used where the housing is structural and the magnetics are not the limiting requirement	Accepts larger reductions per pass than higher-strength grades, so fewer ironing passes and less inter-pass annealing
304 / 316L stainless	Where corrosion matters more than magnetics, or the medium is aggressive	Work-hardens quickly: more passes, inter-stage annealing, more conservative reduction per pass
Aluminium	Lightweight housings where weight is the driver	Different lubricant and die finish; lower press tonnage

What the drawing should specify

Bore diameter and tolerance, and the outside diameter and tolerance - and which of the two is the datum the other is measured from
Wall thickness, and whether it is ironed from a thicker blank
Concentricity or runout between bore and outside diameter
Surface finish (Ra) on the bore and on the outside
Wall thickness variation around the circumference, where the magnetics matter
Magnetic requirements, where the housing is part of the magnetic circuit
Any thread, port or sealing face that forming cannot produce and that must stay a machining operation

Frequently asked questions

Which material is used for a solenoid valve housing?

DT4E electrolytic pure iron where the housing forms part of the magnetic circuit and coercivity or permeability is specified, and DC04 deep drawing steel where the housing is structural. Stainless and aluminium are used where corrosion or weight is the deciding factor.

Why is the housing ironed rather than turned?

Because the bore, the outside diameter and the wall thickness all carry tolerances, and because a thin wall turned from bar converts most of the bar into chips. Ironing forms all three against one tooling axis in the press, so concentricity comes from the tool rather than from re-fixturing.

Does ironing affect the magnetic properties?

Cold work raises coercivity, so the magnitudes involved have to be managed. Balford draws and irons the housing, then carries out magnetic annealing, and the magnetic requirements are treated as part of the drawing review rather than as a separate conversation. See the pages on permeability and coercivity and soft magnetic materials.

Can you hold an armature clearance in the bore?

The bore is formed by the ironing punch and then measured in our own inspection lab - three-point bore micrometers, a concentricity gauge and a 2.5D optical projector for form. Whether a specific clearance is achievable is confirmed during the DFM review against the drawing.

Discuss Your Project

Send the drawing, we will tell you whether ironing removes a machining step

Send the drawing with material, both diameters and the tolerances that matter. Balford reviews the forming route, the ironing passes and the tooling before quoting.

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