The main machine arrives on schedule and then stands idle for a fortnight, and the reason is often a single unobtrusive spare that has not arrived. This looks like a purchasing efficiency problem, but it is really a spare parts strategy problem. What spare parts localisation actually changes is not the price; it is the certainty of the customer's waiting time.
Downtime is defined by the delivery lead time
The loss from a machine standing still accumulates hour by hour, while the waiting time for a spare is usually counted in weeks. When the main machine is already lying on site waiting for nothing but a seal or a filter element, what the customer is really waiting for is an action that can be prepared in advance: holding the spare on site, so that the waiting time is compressed from weeks to zero. That is what spare parts localisation means.
Not every part is worth stocking in advance. Spares preparation ties up capital, requires registration and requires periodic inspection and replacement, and expired or degraded spares in the store are a liability rather than an asset. Separating the parts that should be stocked from those that should not is the key to the whole exercise.
Routine parts and non-routine parts have to be handled separately
The criterion is not the price but the probability of failure and the consequences of failure. Seals, filter elements and heating elements are consumed quickly and replaced as a routine action, so they belong to the routine parts. Main machine components such as the vacuum pump, the Roots pump and the screw oil pump have a long service life but a serious effect when they fail; they belong to the non-routine category and must still be kept available.
| Spare category | Typical parts | Suggested way of obtaining them |
|---|---|---|
| Filtration consumables | Coarse filter elements 150-250-50 and 110-250-50, secondary filter element 110-400-20, fine filter elements 110-600-5 and 150-500-5 | Order on a rolling basis against the consumption cycle and keep a minimum stock on site |
| Seals and fasteners | Seals for the various flanges and end covers | The customer is advised to keep one set in stock |
| Heating and detection parts | Far-infrared carbon fibre heating assembly, infrared level and foam detection probes | Keep one or two sets per machine |
| Main machine components | Vacuum pump X-100, Roots pump JRP-500, screw oil pump ZH | Set up a supply channel with the manufacturer; stocking them on site is not recommended |
Where the lead time difference between imported and domestic parts lies
The difference usually does not lie in transport but in the transaction process. Imported parts pass through ordering, customs declaration, clearance and delivery, and each of these stages involves a queue; in total, the elapsed time usually affects the experience more than the value of the goods. Domestic parts can be bought locally, so their lead time depends more on the manufacturer's own capacity allocation and payment procedure. Compared with each other, the first has the greater uncertainty, and uncertainty is precisely what a site with the machine down can least afford.
Another easily overlooked difference is substitution on specification. Imported parts often have a single original manufacturer model, and once they cannot be bought the substitution path is narrow; domestic model ranges are usually more open and a close equivalent is easier to find, but a substitute has to be checked against the interface dimensions, the material and the temperature rating, and the shape alone is not enough.
What the customer should keep in stock, and how it should be maintained
- Keep one complete set of seals per machine model; once the models are standardised the site no longer has to work out the specification on the spot.
- Stock the filter elements at the current replacement cycle multiplied by a safety factor, and record the production batch so that they are not put out of condition by long storage.
- Link the spare parts list to the equipment register, so that every purchase refers to an equipment number.
- Record the appearance and the specification of each spare on receipt; for rubber parts also record the storage conditions and the storage time.
It should be said clearly that customer stocking does not replace the manufacturer's supply responsibility. The more reasonable division of labour is this: the customer keeps the parts that are consumed quickly, clearly specified and not critical when they fail; the manufacturer guarantees the long-term availability of the main machine components and states a defined way of responding. Which part is whose responsibility, agreed in advance, is far more effective than arguing about it afterwards.
Spare parts localisation is not about piling stock up in advance at the customer's site; it is about bringing the waiting time for every category of part within a range the customer can accept.