Balford manufactures deep-drawn and stamped metal end caps for DC motors, solenoid valves and metal caps for injection valves — with controlled dimensions for assembly.
Most of the custom caps we make are drawn rather than turned: the cap starts as a blank, the wall is formed out of the flange, and the closed end keeps its thickness where it matters. That is why a custom cap can hold its outside diameter and its bore at the same time. Materials and grades are listed on the metal stamping materials page.
Deep-drawn metal end caps for compact DC motor assemblies.
Stamped metal caps for methanol-injection solenoid valves and similar applications.
End caps protect internal assemblies, carry bearings and seal the working envelope. Balford produces deep-drawn and stamped metal end caps for DC motors and solenoid valves, plus metal caps for injection valves, with controlled roundness and assembly-fit dimensions.
An end cap can be drawn, stamped or machined, and the choice is made on quantity and geometry rather than on preference. The four routes below cover every cap we quote.
| Route | When it is the right one | What it is good at | Where it stops |
|---|---|---|---|
| Deep drawing | The cap has a wall and a closed end, and the wall is formed out of the flange — the usual route for motor and solenoid end caps | A seamless wall and base, wall thickness controlled through the draw, and outside diameter and bore held in the same part | Very thick walls, or a shape with undercuts the die cannot release |
| Progressive or transfer stamping | Flat or shallow caps, or a cap with holes, slots and forms that have to be produced at volume | Several stations in one tool, so features are added without re-fixturing the part | Draws deeper than the strip can carry through the tool |
| CNC machining from bar | Prototypes, small batches, or a cap whose features cannot be formed — cross-drilled ports, tight bores, threads | No tooling cost, free-form geometry, dimensions set directly from the drawing | Piece price at volume, and the material lost cutting from solid. Near-net pre-forms for machining (forging, cold extrusion, casting, powder metallurgy) are bought in and finished in house |
| Machining after forming | A drawn or stamped cap that still needs a faced end, a reamed bore, a thread or a cross hole | Keeps the seamless wall and adds the precision features in the same plant | Adds an operation and its lead time, and the datum has to be defined on the drawing |
The presses run from 25 t to 350 t with a maximum draw diameter of 250 mm, which is the envelope a drawn cap has to fit. Where a cap is machined, the turning, milling and drilling run in house; plating, passivation and bulk heat treatment are carried out by audited partner companies and are declared on the quotation.
The material follows the function: drawability for a deep cap, corrosion resistance for a wetted or outdoor cap, and permeability where the cap is part of a magnetic circuit.
| Material | Why it is chosen for a cap | Typical finish |
|---|---|---|
| Carbon steel DC01–DC04, SPCC | The default for drawn caps: drawability is the deciding property, and the grade sets how many stages the wall needs | Zinc plating or blackening by an audited partner company |
| Stainless steel 304 / 316L | Corrosion resistance, and non-magnetic where the cap must not close a magnetic path | Passivation or electropolishing by an audited partner company |
| Electrical pure iron DT4E class | Caps that sit in the magnetic circuit and need high permeability and low coercivity | Heat-treatment route agreed on the drawing and declared on the quotation |
| Aluminium 5052 / 6061 | Weight-critical and non-magnetic caps | Powder coated (small parts through a partner’s conveyor line) or left mill finish |
Grades and their forming behaviour are set out on carbon steel for stamping and deep drawing and stainless steel.
Real projects from Balford's production history:
Deep-drawn end caps for DC motors and stamped metal caps for solenoid and injection valves.
Roundness and concentricity are maintained through tooling and in-process checks; final measurements are reported with the part.
Yes — CNC turning, facing and hole operations are performed in-house after deep drawing.
Yes, and for a prototype or a small batch it is usually the better route: there is no tooling cost and the dimensions come straight off the drawing. It stops being economic at volume, because the piece price carries the machining time and the material cut away from solid bar. The usual answer for a cap that is needed in series is to draw it and then machine only the features the draw cannot produce — a faced end, a reamed bore, a thread or a cross hole.
Yes. Series production runs on tooling built for the annual volume — a single-station die, a progressive die or a transfer tool — with in-process inspection at defined intervals and a dimensional report per batch on request. Sample lead time is 15–30 calendar days for a single-operation stamping die and 30–60 days for progressive or transfer tooling, counted from the confirmed drawing; the series dates follow the tooling. PPAP Level 3 documentation is the normal submission for a new programme.
Send us your 2D drawing or STEP/IGES model. We will review material, tolerances, forming requirements and production volume before quoting.