In this guide 6 sections
Parts run short because dealer orders arrive after the long-lead items should already have been ordered, and a flat annual forecast hides the seasonal peak. Gearboxes, cylinders and tyres take months. A rolling plan that works backward from the sowing date exposes the gap early, while there is still time to order.
The shortage is decided months before it is felt
A seed drill sells in a narrow window. Dealers want stock on their lots weeks before the rains arrive, so by the first panicked call the purchase file has already fixed the shortage.
Look back at last season. Find the part that stopped the line and the date its order went out, because the gap to the day it reached stores is your real lead time.
Most owners find the purchase order went out after the dealers confirmed their bookings, not before, and that is the pattern to break.
Four causes that stack on top of each other
No single failure explains it. A flat monthly forecast spreads a seasonal peak evenly, so the buyer orders a quarter-year of gearboxes in the quiet months and runs dry in the busy one.
Bought-out items such as PTO shafts, bearings, cylinders and tyres carry long lead times from a handful of suppliers, and one late shipment holds up a batch of cultivators.
Dealers also place orders late and change them. Each change reaches purchasing as a phone call, a notepad scribble or a WhatsApp message, and nobody can total those at month end.
- Flat forecast across a seasonal peak
- Long lead gearboxes, cylinders and tyres
- Dealer orders confirmed late or revised
- Safety stock set once and never revisited
Build the planning view backward from the season
Start with the date the dealer needs units on the lot, then subtract transport, final assembly, painting and welding from it, working back one stage at a time. That date is when parts must already sit in the stores racks, which is a different thing from when they should be ordered.
Subtract each part’s supplier lead time from that date to get a latest order date per item, then sort the whole list by it. Risky items rise to the top.
A simple table with part, supplier, lead time, quantity needed and latest order date is enough to begin with, and anything past its latest order date shows in red.
Turn dealer signals into a number
Dealer enquiries, advance bookings and last season’s sell-through are all signals, so capture them in one place and turn them into a unit forecast for each model.
Run that forecast through the bills of materials, so rotavators become a count of gearboxes, blades, flanges and shear bolts for each week of the season. Compare it with stock and open orders.
The difference is what to buy. It is plain subtraction, which fails only when a bill of materials is stale because engineering changed a gearbox mount and nobody updated the list.
- Dealer bookings by model and week
- Last season’s sell-through by dealer
- Forecast exploded through the bill of materials
- Net need after stock and open orders
Review the plan every week, not once a year
Hold a short weekly review in the months before the rains, with the production manager, the buyer and the sales head reading the same page. Late suppliers and changed dealer orders are discussed with numbers in front of everyone, never from memory of a phone call last Tuesday.
Pick one gearbox or cylinder this week. Place its order against forecast rather than confirmed dealer orders, because carrying a few spare units for a month costs far less than an assembly line that stands idle. Stock is cheaper than waiting.
Season parts planner
Each long-lead part gets a row with part number, supplier, lead time in weeks, units per machine, forecast machines, stock on hand and open purchase orders. The last four columns give net need, season start date, latest order date and a mark for on track, at risk or late.
Open a blank worksheet to printQuestions owners ask
Which parts should we plan first?
Start with items that take longest to arrive and that no other supplier can replace quickly, which usually means gearboxes, hydraulic cylinders, tyres and castings.
How much safety stock is enough?
Enough to cover one supplier delay for the parts that stop a whole machine, so check it against last season’s late shipments and adjust it each year.
Can a spreadsheet do this planning?
For a handful of models, yes. It breaks when bills of materials change often or when dealer orders arrive daily, because the sums need to rerun automatically every time a number changes.