Inventory control

Buffer stock is the minimum level of stock a business holds (1) as a safety net to avoid running out if demand rises or a delivery is delayed (1).

An inventory control diagram plots stock level against time as a sawtooth (Knowledge 1). Stock falls as it is used; when it reaches the reorder level, the business places a new order (Application). Over the lead time, stock keeps falling towards the buffer (minimum) level; the delivery then replenishes stock by the reorder quantity back up to the maximum (Application). This lets the business reorder in time to avoid running out while not holding more stock than necessary (Analysis 1).

JIT would let FreshFoods hold minimal stock, freeing the cash it currently ties up in ingredients (Knowledge + Application). Freed cash improves FreshFoods' cash flow and liquidity, so it can pay suppliers and staff without borrowing, reducing interest costs (Analysis).

JIT is also especially valuable for a food producer because ingredients are perishable (Knowledge + Application). By holding little stock and using ingredients as they arrive, FreshFoods cuts waste from spoilage and lowers storage/refrigeration costs, reducing overall costs and improving margins (Analysis).

Switching to JIT could bring BuildRight real savings. Its large buffer stocks tie up working capital and rack up warehousing and holding costs; moving to JIT would release that capital, improve cash flow, and cut storage overheads and stock obsolescence — funds BuildRight could redeploy elsewhere. For a materials supplier holding bulky, high-value inventory, these savings could be significant.

However, JIT is risky for BuildRight's situation. Construction demand can be lumpy and urgent, and site customers expect materials available on demand; with minimal stock, a supplier lead-time overrun or a supply-chain disruption would leave BuildRight unable to fulfil orders, losing sales and damaging its reputation for reliability. Holding buffer stock (JIC) is partly what makes BuildRight a dependable supplier.

Whether to switch therefore depends on the reliability of BuildRight's suppliers and the predictability of demand. If it has reliable, local suppliers with short lead times and fairly steady demand, a partial move to JIT — trimming excess buffer stock on fast-moving, easily-resupplied lines while keeping buffers on critical or long-lead-time materials — would capture much of the working-capital saving without leaving BuildRight exposed. A full switch to JIT would only be wise if its supply chain is genuinely dependable, which for a construction supplier is often not guaranteed.

JIT has clearly served AutoBuild well in cutting costs, but its reliance on a single overseas supplier raises the question of whether it is now too exposed.

The case for continuing with JIT. JIT keeps AutoBuild's stockholding and warehousing costs low — car components are numerous and expensive, so not holding large inventories releases substantial working capital and improves cash flow. It reduces waste and obsolescence (components don't sit unused as models change) and supports lean, efficient assembly. For a competitive car maker, these cost savings help protect margins and price competitiveness.

The case against. However, AutoBuild's JIT depends on one overseas supplier and holds little buffer stock, so any disruption — a shipping delay, a port closure, a supplier failure — would halt the assembly line entirely, costing far more in lost output and missed orders than JIT saves. Long, single-sourced overseas supply chains are fragile, as recent global disruptions showed. AutoBuild also has no fallback if the supplier raises prices or fails.

Judgement. On balance, AutoBuild should keep the JIT approach but reduce its supply-chain vulnerability rather than abandon it. JIT's cost and cash-flow benefits are real and worth keeping, so a wholesale return to large buffer inventories would sacrifice a genuine competitive advantage. But relying on a single overseas supplier is the weak point: AutoBuild should build in resilience — holding a small buffer of critical components, and dual-sourcing (adding a second, ideally nearer, supplier with shorter lead times) — so it keeps most of JIT's savings while protecting itself against the disruption that could shut its line. The right answer depends on how reliable and resilient its supply chain is: the less dependable, the more buffer and back-up sourcing AutoBuild needs.

JIT and JIC are opposite answers to the same question — how much stock to hold — and each trades cost against security. Whether PackWell should adopt JIT over JIC depends on its supply chain, its demand, and the cost of running out.

The case for JIT. JIT would let PackWell hold minimal raw-material inventory, arriving just as needed on the line. This releases working capital previously tied up in stock, improving cash flow and liquidity, and cuts warehousing costs and waste (less obsolete or damaged material). It supports lean, efficient production and lower unit costs, helping PackWell compete on price. For a manufacturer with tight margins, these savings are attractive.

The case for JIC. However, JIC — holding buffer stock — protects PackWell against supply-chain disruption. If demand suddenly rises or a delivery lead time overruns, buffer stock lets PackWell keep the line running and fulfil orders, protecting its reputation as a reliable supplier. JIC also unlocks bulk-buying discount agreements. The downside is that it ties up working capital, raises holding and warehousing costs, and risks materials becoming obsolete. With JIT, by contrast, a single supply failure — with no buffer — could halt production, and the lost output and customers could cost far more than JIT saves.

What it depends on. The right choice for PackWell depends on several factors. It depends on supplier reliability — reliable, local suppliers with short lead times make JIT viable; unpredictable or distant supply favours JIC buffers. It depends on demand predictability — steady demand suits JIT, volatile demand favours buffer stock. It depends on the cost of a stock-out — if running out loses key customers or contracts, more buffer is wise. And it depends on PackWell's working-capital position — tight cash pushes towards the lower inventory of JIT.

Conclusion. On balance, PackWell should lean towards JIT but not adopt it in a pure, absolute form. JIT's cash-flow and cost benefits are real and worth capturing, so holding excessive 'just-in-case' inventory across the board would waste working capital and warehousing space. But a pure JIT with zero buffer leaves PackWell dangerously exposed to supply disruption. The best approach is a hybrid: run JIT for reliably-supplied, fast-moving materials to release cash, while keeping a modest buffer of critical or long-lead-time items to protect against disruption. Whether PackWell should tilt further towards JIT or JIC ultimately depends on how reliable its suppliers are and how costly a stock-out would be — the more dependable the supply and the lower the stock-out cost, the more it can rely on JIT.