Winding skill sits with a handful: HR for agricultural pump makers

It is the week before the first good rain. Dealer calls start at nine. Stores has copper, slot paper and varnish. The fitters have assembled pump ends waiting on stators. Then the senior winder phones to say his mother is unwell and he will be away for four days. The second winder is already stretched on the open-well range. By evening the owner is deciding whether to hold dispatch or let a junior wind the submersible stators alone.

Our agricultural pump makers page opens its list of strains with winding. Turns, gauge and insulation are judged by two or three seniors. This post is about why it stays that way and what to change before next season.

The winding data sheet gives turns per coil, wire size and connection. A senior winder knows far more. He feels when the slot liner is seated and when it will split under the wedge. He knows how hard to pull enamelled copper before it thins. He judges slot fill by the push it takes to drop the last turns in. For water-filled submersibles, he handles the insulated winding wire so its covering never nicks on the core edge.

• Coil forming. Even turns on the former, no crossed wires, the right overhang so end windings clear the housing.
• Insertion. Slot paper folded and placed, coils dropped without scraping enamel, wedges driven home.
• Joints and leads. Brazed or crimped joints sleeved properly, lead wire routed so it cannot chafe in service.
• Lacing and shaping. End turns laced tight and pressed into shape, so vibration in the borewell does not rub them through.
• Varnish and bake. Dip time, drip time and oven cycle followed, so the stator cures right through and not only on the surface.
• Self-check. A quick resistance and insulation reading before the stator leaves the bench.

Winding is a slow trade to pick up and a hard one to observe. Most of it happens inside a slot, under the senior's fingers. Juniors in many units are kept on coil forming or varnish dipping for years, because the senior fears a ruined stator will be blamed on him. Nobody tells the junior what step comes next or what it pays. Some seniors also guard the skill. It is their security in a trade where the owner's dependence on them is obvious.

Pay adds to the problem. Many units pay winders a day rate with a small extra per stator in the season. A junior on that basis sees no reason to master the hard models. A senior sees no reason to hand over the work that makes him valuable.

• Assembled pump ends sit idle waiting for stators, and dealer orders slip in the weeks that matter most.
• A less sure hand winds under pressure, and a weak joint or nicked insulation leaves the plant inside a sealed motor.
• Burnt sets return through dealers after a few weeks in a farmer's borewell, when the cause can no longer be traced.
• The service team spends the season on farm visits and replacement claims instead of new installations.
• The senior who stayed works double shifts, and the next resignation becomes more likely.

You cannot write down a feel completely. You can write down enough that a learner knows what to aim for and a checker knows what to look at. Start with one card per pump model, kept at the winding bench.

Model and rating: as on the nameplate drawing.
Wire: size, insulation type, supplier batch noted on each job.
Coils: turns per coil, former size, coils per group.
Slot work: liner type and fold, wedge type, any extra phase paper.
Connection: diagram copied by hand, lead wire size and length.
Lacing: points to lace, cord type, shaping press setting.
Varnish: dip time, drip time, oven temperature and hours.
Bench checks: resistance per phase and insulation reading before release.
Common faults on this model: written by the senior in his own words.
Card owner: the senior winder, who updates it when anything changes.

Next, stamp or tag each finished stator with a winder number and a varnish date. When a set comes back burnt, the tag tells you who wound it and in which batch. Read the returns monthly with the winders, not as blame but as learning. The HR reporting page for pump makers describes a simple way to keep that record by person and month.

1. 1

   Stage one: coil former and varnish

   The learner forms coils for one model and runs the dip and bake. Signed off when ten coil sets in a row pass the senior's check without rework.

2. 2

   Stage two: insertion on simple models

   Monoblock and open-well stators first, with the senior looking into each slot before wedging. Signed off on a run of stators that pass bench and test-bay checks.

3. 3

   Stage three: submersible stators

   Water-filled motors with insulated wire, close slot fill and long leads. The senior watches the first set fully, then spot checks. Signed off when returns from the field show no fault traced to the learner.

4. 4

   Pay that moves with each stage

   Each stage carries a published rate. The learner knows the rate attached to the next signature.

5. 5

   An allowance for the senior who teaches

   It is paid whenever one of his learners clears a stage. It turns guarding the skill into earning from sharing it.

The pump makers' skill-building guide sets out how to run this kind of signed skill list. Keep the sign-off sheet in the employee file, not in the senior's drawer.

Dispatch surges before sowing and in the dry months when water tables drop. Nobody teaches well in that rush. Put the winding cards, the stage tests and the new learners into the slack months, when stators can be wound slowly and the senior has time to watch. Casual hands who formed coils well last season go to the top of the recall list. Masks and ear plugs for the casting and machining bays belong on the same calendar; see the safety page for pump makers.

• Sit with your senior winder and agree which two juniors he will teach this year.
• Write a winding card for your best-selling submersible model, in his words.
• Start tagging stators with the winder's code and varnish date from next Monday.
• Publish the three stages and what each pays.
• Count last season's burnt-set returns and how many you could trace to a winder.

Season planning, casual hands and field service for the wider group are on our hub for farm equipment and pump makers. Transformer shops face a close cousin of this problem, covered in our post on coil winders in transformer works.