A machine stops. The technician opens the parts cabinet. The shelf is empty. The part was used three weeks ago and nobody reordered it.
This is an MRO inventory failure. And it is the most common — and most preventable — cause of extended downtime in Indonesian factories.
MRO (Maintenance, Repair, and Operations) inventory includes all the materials and supplies a factory needs to keep equipment running. It is not the raw material going into your product. It is everything that supports the production process itself.
What Counts as MRO Inventory?
MRO inventory falls into four broad categories:
Spare parts. Bearings, belts, seals, motors, pumps, valves, sensors, circuit boards, and any component that can fail and needs replacement. These are the highest-value and most critical items in MRO stock.
Consumables. Lubricants, hydraulic oils, greases, filters (air, oil, coolant), gaskets, O-rings, welding rods, grinding discs, and cleaning solvents. These items are used up during maintenance and production and must be replenished regularly.
Tools and equipment. Wrenches, screwdrivers, multimeters, torque wrenches, calibration tools, hoists, slings, and lifting equipment. While these are reusable, they still require tracking for availability, calibration, and replacement.
Safety and facility supplies. PPE (helmets, gloves, safety glasses, respirators), first aid kits, fire extinguisher refills, spill kits, lighting, brooms, and janitorial supplies. These keep the facility compliant and safe.
In a typical Indonesian manufacturing plant, MRO inventory can represent 5–15% of total inventory value. But unlike raw materials, MRO items are not consumed by the product — they are consumed by the equipment.
How MRO Inventory Differs from Production Inventory
Raw materials and finished goods follow a predictable consumption pattern. You know how much steel you need per unit, how many cartons per shift. MRO inventory is fundamentally different:
| Aspect | Production Inventory | MRO Inventory |
|---|---|---|
| Demand pattern | Predictable, forecastable | Sporadic, failure-driven |
| Lead time | Negotiated, stable | Urgent when stockout hits |
| Cost per item | Often high | Varies widely |
| Number of SKUs | 10s–100s | 1,000s–10,000s |
| Criticality | Any shortage stops production | Some items stop production, others don't |
| Supplier | Few, consistent | Many, fragmented |
The unpredictability is what makes MRO inventory management hard. A seal that lasts two years on one pump fails in six months on another. You cannot forecast that with a simple moving average.
The Four Common Problems with MRO Inventory
1. Overstock
The most common response to uncertainty is to stock everything "just in case." Parts sit on shelves for years. Some expire. Some become obsolete when equipment is decommissioned.
Overstock ties up capital. A bearing worth Rp 500,000 sitting unused for three years cost you more than the bearing itself — through lost interest, warehouse space, and the risk of damage or corrosion.
2. Stockouts
The opposite problem — and equally common. A critical pump breaks down, but the mechanical seal is not in stock. The factory faces two bad choices: wait days for delivery, or pay 3–5x the normal price for emergency air freight.
In Indonesian factories, stockouts on high-criticality parts are often the result of not tracking usage data. Nobody knows how many times a part was used last year, so nobody knows how many to keep on hand.
3. Obsolete Parts
Equipment changes. Upgrades happen. Lines are decommissioned. But the spare parts for old equipment stay in inventory, taking up space and tying up budget.
Many factories discover obsolete MRO only during annual stocktaking — or when nobody can remember what machine a part belongs to.
4. No Minimum Stock Levels
Without defined minimums and reorder points, every purchase is reactive. Someone notices a part is low and places an order. Or they don't notice, and the part runs out.
This ad-hoc approach creates a vicious cycle: emergency purchases breed distrust of the system, which leads to over-ordering "just in case," which creates overstock for some parts and stockouts for others.
How to Optimize MRO Inventory
ABC Analysis
Classify every MRO item by annual consumption value:
- A-items — 10–20% of SKUs, 70–80% of spend. These are your high-value, critical spares. Tight controls, frequent cycle counts.
- B-items — 20–30% of SKUs, 15–20% of spend. Moderate controls.
- C-items — 50–70% of SKUs, 5–10% of spend. Nuts, bolts, cheap consumables. Simple min-max management.
For most factories, 20% of MRO SKUs consume 80% of the budget. ABC analysis tells you where to focus.
Set Min-Max Levels
Every stocked part needs three numbers:
- Min level — The quantity at which you must reorder. Usually based on lead time × average monthly consumption, plus safety stock.
- Max level — The most you want to hold. Avoids tying up capital in excess stock.
- Reorder point — Usually set at min level, or slightly above if lead times are unreliable.
These levels must be reviewed periodically — at least every six months — because consumption changes.
Standardize Across Assets
If you have five conveyor motors from three different suppliers, you probably have five different bearing part numbers for the same bearing size. Standardizing part numbers and consolidating suppliers reduces the total SKU count, which simplifies purchasing and reduces inventory value.
Use a CMMS with an Inventory Module
Spreadsheets and paper records cannot keep up with the volume and velocity of MRO consumption. You need a system that tracks every part, every transaction, and every reorder.
Consequences of Poor MRO Inventory Management
Unplanned downtime. When a critical part is not in stock, the machine stays down until it arrives. At an average cost of Rp 10–50 million per hour of production stoppage, one stockout can erase the annual savings of lean inventory practices.
Rush shipping costs. Emergency orders mean premium freight. Air freight costs 5–10x sea freight. In some cases, factories charter private vehicles to deliver a single bearing.
Wrong parts ordered under pressure. When a machine is down and production is screaming, people make mistakes. Wrong parts get ordered, which means the machine stays down longer.
Lost productivity. Technicians spend 20–30% of their time searching for parts and tools, according to industry studies. That is time not spent actually fixing equipment.
Inflated inventory carrying costs. Overstocked parts tie up capital that could be used elsewhere. Carrying costs (storage, insurance, obsolescence, opportunity cost) average 20–30% of inventory value per year.
How a CMMS with Inventory Module Helps
A purpose-built CMMS inventory module transforms MRO management from reactive firefighting to proactive control.
Real-time stock visibility. Every issue and receipt is logged instantly. No more wondering if a part is actually in stock.
Part-to-asset linking. Every spare part is linked to the assets it fits. When a work order is created for a pump, the system shows all parts that belong to that pump's BOM.
Auto-reorder triggers. When stock hits the reorder point, the system generates a purchase requisition automatically. No manual monitoring needed.
Usage analytics. See which parts are consumed fastest, which assets consume the most spares, and where the budget is going. Data drives better min-max decisions.
Serial number and lot tracking. Trace every part to its supplier, purchase date, and installation history. Critical for quality issues and warranty claims.
Cycle counting. Scheduled partial counts keep inventory accuracy high without full shutdowns for stocktaking.
What to Do Next
If your factory is still managing MRO inventory with spreadsheets, sticky notes, or tribal knowledge, you are not alone — but you are also leaving significant savings and uptime on the table.
OpexMX is a CMMS built for Indonesian manufacturing teams. Our inventory module is designed to handle the complexity of MRO — thousands of SKUs, multiple suppliers, and high-stakes stock decisions.
Contact us for a demo or start your free trial today.