Factory Size and Fit: Which Tier Suits Your Order

Assembly businesses fall into recognisable groups, and the grouping is not a ranking. A factory organised around very large orders is not better or worse than one organised around many small ones; it is a different instrument, and the question is which one fits the work being placed.

Factory size is a useful proxy for that, because the size determines what the plant is built to do well: throughput, flexibility, or a narrow specialism. A customer who understands which group suits the order avoids two common disappointments, the small job that is refused or neglected and the large job that is accepted by a plant without the capacity to sustain it.

Plants Built for Throughput

A large plant amortises its preparation across long runs. The line is configured for a product and left that way, the material is purchased in volume, and the cost per unit falls with the quantity. On a stable, high-volume requirement this is the most efficient arrangement that exists.

What such a plant does not do well is change over frequently. Each conversion consumes line time that would otherwise be productive, and a small order occupies the same interval as a large one while contributing far less. The consequence for a small customer is a high price, a long date, or a polite refusal.

This group is the right choice when the product is mature, the volume is substantial and the requirement is unlikely to change. It is the wrong choice for a development programme in which the board changes every few weeks.

Plants Built for Flexibility

The middle group is organised around many products of modest quantity. Its competitive advantage is the changeover: prepared kits, stored programmes, retained stencils and a routine that converts the line quickly rather than regarding each conversion as an event.

Such a plant can accept a small batch, a mixed order and a revision that arrives mid-project, and it can do so without disturbing a larger commitment, because the planning assumes that the mix is variable. Its capacity is smaller in absolute terms, but it is available in the shape that development work needs.

The trade-off is price at volume. Where a product grows into a sustained high-volume requirement, the flexible plant may not be able to match the cost of the large one, and the transition has to be planned rather than assumed.

Specialists and Small Workshops

At the smaller end, two different things are often grouped together. A specialist may be a small operation with deep experience of one class of product, one material or one process, and it can be the best available choice for a board that sits outside the mainstream.

A workshop with older equipment and no organised process is a different proposition. It may be adequate for a simple board at a low price, and it is not a place to send a design that depends on fine pitch, controlled paste volume or traceable records.

The distinction is worth making explicitly, because the two are similar in size and very different in capability. The questions that separate them are about process control rather than about equipment: whether the paste is measured, whether the profile is established for the board, whether a first article is verified and whether the results are recorded.

Matching the Order to the Batch Pattern

The decision is easier when the requirement is described as a pattern rather than a number. A single order of fifty boards, a repeating order of fifty boards each quarter and a one-off order of fifty boards followed by two thousand in six months are three different requirements.

The first suits a flexible plant and rewards retaining the stencil and the programme. The second suits the same plant and becomes progressively cheaper. The third may justify starting with the flexible plant and planning a transfer, or starting with a plant that can scale, depending on how certain the volume forecast is.

What should be avoided is placing the development work where the production will eventually be, if that plant finds small orders inconvenient. The records created during development are the most valuable asset in the transfer, and a supplier who is not interested in the small order is unlikely to be attentive to the records either.

<img src="https://www.gopcba.com/wp-content/uploads/2024/10/vektornyj_smart-obekt.webp" alt="production line configured for a small order batch pattern” />

Questions That Reveal the Group

A plant’s position becomes clear from a few answers. How many different products are on the line this week? How long does a conversion take for a product that has been built before? What is the smallest order that makes sense, and what does the price do between that quantity and ten times it?

The reply to the last question is particularly informative. A figure that falls sharply with quantity indicates a plan built for volume; a figure that falls modestly indicates that the preparation is already small, which is what a flexible plant is designed to achieve.

The verification of the answers is the same in every case: a small order placed first, observed for how the data was reviewed, how the questions were raised and whether the delivery matched the description. The operations themselves are unchanged from plant to plant: SMT assembly, through-hole assembly where inserted parts are used, PCBA testing and the controls under quality management.

The Transition Between Groups

Products change group as they mature, and the transition is where most of the avoidable cost appears.

A design that begins with a flexible plant and grows into a sustained requirement may eventually be cheaper to build elsewhere, and the change is manageable if it is planned: the stack-up, the material specification, the approved substitutions, the test limits and the recorded parameters all travel. What does not travel is the habit, so the new plant should build the product while the volumes are still modest, before the requirement becomes critical.

The reverse transition is more difficult. Moving a product back to a flexible plant after the volume falls is straightforward in principle, but the records have to exist at the plant that is being left, and they frequently belong to a system the customer never sees.

The practical protection in either direction is to hold the documents that define the product, rather than only the boards that embody it. Where the customer can produce the stack-up, the material list, the approval record and the acceptance criteria on demand, both transitions become a matter of planning rather than rediscovery.

One further question is worth asking of any plant, whatever its group: who would answer a technical question about the board, and how quickly. The answer describes the working relationship that the order will create, and it is observable before any money is committed.

FAQ

Is a larger factory always better? No. It is better for a stable high-volume requirement and worse for a changing one, for the same reason: preparation has to be amortised.

What distinguishes a specialist from an unorganised workshop? Usually process control rather than size: whether the deposit is measured, the profile established for the board and the results recorded.

How should a growing product be planned? By describing the pattern of orders rather than a single quantity, and by keeping the records that make a transfer possible if the volume justifies one.