Sourcing assemblies from India: supplier models and ramp

Why an assembly is not a part with more lines

A single part programme has one process to control and one drawing to approve. An assembly programme has as many processes as it has components, plus the build, the test and the packing. The buyer is no longer managing a supplier. The buyer is managing a small supply chain that happens to sit behind one invoice.

That changes the questions. Instead of asking whether a plant can hold a tolerance, the buyer asks whether it can receive, inspect, store and issue components, control revisions, build to an instruction and test the result. Those are different capabilities, and a good moulding plant does not automatically have them.

The commercial structure changes too. An assembly quote carries component material, labour, test, scrap and freight, and the split between them decides where the risk sits when something moves.

The buyer also inherits the assembler's scheduling problem. A missing component stops the line, and the assembler may not have the authority to expedite a part bought from a nominated source. Decide who chases the shortage before the first one happens.

An assembly also changes the inspection question. Instead of asking whether a dimension is inside tolerance, the buyer asks whether the unit works, and that answer depends on the fixture, the test and the operator as much as on the parts.

The sub tier problem

Most assembly failures in an offshore programme start one level down. A plated terminal arrives with a thickness at the low end of its range. A moulded cover arrives from a second tool with a slightly different shrink. A purchased screw changes from one coating to another without a drawing change.

The assembler sees these parts as conforming, because each one passes its own inspection. The assembly then fails, and the failure is discovered after the parts have travelled, which makes the investigation slow and the corrective action expensive.

Control the sub tier by naming the sources, requiring approval before a change, and asking for the certificate that links to the batch in the build. Where the sub tier is critical, ask for the first article from that supplier, not a certificate of conformance alone.

A useful check is to ask the assembler to show the incoming inspection record for the three components with the tightest tolerances. If the record is a signature with no measurement, the sub tier is uncontrolled whatever the certificate says.

Four supplier models

Indian suppliers approach assembly in four broad ways, and each has a different risk profile. A component maker that assembles its own parts controls the fit but may buy everything else from the open market. A dedicated assembler controls the build and the test but depends on its sub tier for quality. A tier one integrator manages the chain and usually carries the documentation, at a price. A trading house coordinates and invoices but may not own the process at all.

The model should follow the programme. A simple bracket with two inserts suits a component maker. A multi part electrical assembly with a functional test needs someone who owns the test station and the traceability.

The commercial model matters as much as the process. Some assemblers prefer free issue components because it removes material from their balance sheet. Others prefer to buy and add a margin, because it gives them control of the schedule. Neither is wrong, but the choice changes who carries the inventory risk.

Whichever model you choose, visit the line that will build the product. A supplier that cannot show you the station, the fixture and the test box has not yet decided how the assembly will be made.

Traceability and documents

Traceability means that a finished unit can be connected to the components inside it and to the process that built it. In practice that is a label with a batch or serial number, a build record and a component issue record. It does not need software, but it does need discipline.

Ask for the documents before the first shipment: the process flow, the control plan, the work instruction, the test specification and the first article. Then check that the build record the operator fills in matches the control plan the quality manager signed.

Where the customer requires a declaration, such as a material or a country of origin statement, name it in the RFQ. A declaration produced after the shipment is a favour, not a process.

Serialisation is worth the effort where a failure has to be traced to a batch. A serial number on the label, recorded against the component batches used that day, turns a recall from a whole shipment into a defined set of units.

Test at source, not at destination

A test performed at the destination is a sorting operation, not a control. By the time a unit reaches the customer, the cost of the failure includes the freight in both directions, the handling, the paperwork and the delay. The same failure caught at the build station costs a rework minute.

Put the test station in the supplier's plan and make it part of the price. Specify the equipment, the fixture, the cycle time and the acceptance limit. Ask for the daily test log and the reaction plan, and check the log on a call rather than waiting for the audit.

Where the test equipment is expensive, agree who buys it and who owns it. A test box owned by the buyer and maintained by the supplier is workable, provided the calibration and the repair route are written down.

Agree what happens to a unit that fails. Rework, retest and scrap each have a cost and a record. A rework that is not recorded looks like a first time pass in the data, and the process then appears better than it is.

Packing and export

An assembly is usually bulkier and more fragile than the parts inside it. Packing has to protect a finish, hold a position and survive a sea leg. Ask for a packing drawing, a drop test result on the packed carton if the product is fragile, and a pallet pattern that fits the container.

Check the label against the customer's goods in process. A missing barcode or a wrong quantity on the label turns a good shipment into a rejected one at the warehouse, and the rejection is charged to somebody.

Decide the Incoterm early and make sure both sides understand where risk moves. The cost of the sea leg belongs in the landed cost model, and so does the cost of the buffer stock that covers the transit time.

Ask for a packing drawing and a photograph of a packed pallet before the first shipment. It is cheaper to correct a pallet pattern on paper than to rebuild a container load at the port.

A ramp plan with exit criteria

A launch that moves from a sample to full volume in one step has no place to catch a problem. Ramp in stages, with a written criterion for each stage and a named person who signs it off.

Review the data weekly during ramp, not monthly. A yield problem that appears in week one is a process adjustment; the same problem found in week six is a shipment hold.