MRO Parts: What is MRO, and how can maintenance departments procure replacement parts more quickly?

A machine is down, the replacement part is missing, and the order is just a note sitting in the purchasing department’s drawer. In many manufacturing facilities, it’s not the lead time that determines the duration of a shutdown, but rather the process of placing the order. This article explains what MRO parts are, which systems are involved in spare parts procurement, and how maintenance can move away from paper-based processes in five steps.

MRO stands for Maintenance, Repair, and Operations and refers to all replacement parts, tools, and consumables used to maintain equipment and ensure operations. MRO parts can be procured quickly when maintenance orders them directly from pre-stored supplier catalogs, using approval rules that don’t slow things down in the event of a breakdown.

The most important points at a glance:

• MRO parts are replacement and wear parts, tools, and consumables used for maintenance, repair, and operations. They are not incorporated into the final product and are classified as indirect requirements.
• Three systems typically work together in spare parts procurement: maintenance software for maintenance and spare parts inventory, ERP for accounting and inventory management, and a procurement platform for placing orders with suppliers.
• Not every spare part requires the same process. Critical parts belong in the warehouse, standard parts in a catalog, and custom parts require a quick inquiry to the manufacturer.
• The greatest time loss occurs between the identification of a need and the placement of an order, not with the supplier. According to HTWK Leipzig, placing an order at the reference company takes an average of 38 minutes.
• Approval rules for maintenance should allow spare part orders up to a specified value threshold to be processed without delay.

Fabian von Kleinsorgen works at simple system with purchasing and maintenance teams from mechanical engineering and manufacturing who are digitizing their spare parts procurement. In the following, you’ll learn how MRO parts differ from C-parts, which system handles which task, and which rules truly save time in the event of a breakdown.

What Are MRO Parts?

MRO parts are all materials, spare parts, and consumables that a company needs to keep machines, equipment, and buildings operational. They are not incorporated into the product sold and therefore fall under indirect requirements.

Definition: In procurement, MRO (Maintenance, Repair, and Operations) refers to all replacement parts, wear parts, tools, and operating supplies required for the maintenance, repair, and ongoing operation of equipment, but which are not incorporated into the final product.

The term is divided into three categories:

• Maintenance: planned activities such as inspections, lubrication, and the replacement of wear parts before they fail.
• Repair: reactive measures taken after a failure. Every hour counts here because the equipment is down.
• Operations: Consumables for day-to-day operations, such as protective equipment, cleaning supplies, oils, batteries, and fasteners.

Typical MRO parts include bearings, seals, O-rings, V-belts, pneumatic components, fuses, lubricants, tools, and personal protective equipment. Maintenance itself is divided, according to DIN 31051, into maintenance, inspection, repair, and improvement. MRO parts are used in all four areas.

MRO in aviation: In this context, MRO stands for Maintenance, Repair, and Overhaul and refers to aircraft maintenance facilities. In the procurement departments of industrial companies, the term always refers to the “Operations” variant.

What is the difference between MRO parts and C-parts?

MRO describes a part’s intended use, while C-parts describe its value. Many MRO parts are also C-parts: low unit price, high order frequency. A critical replacement part for a specialized machine, on the other hand, is an MRO part but not a C-part because it is expensive and difficult to procure.

Why ordering spare parts via paper slips and email takes too long in the event of a malfunction

Spare part orders take too long during a breakdown because the request passes through several stages before a supplier even learns of it. There are typically five handoffs between the workshop and the supplier:

1. The maintenance technician notes the part on a piece of paper or in an email.
2. Purchasing looks up the part number, supplier, and price.
3. For unknown parts, a quote is requested.
4. The order awaits approval.
5. The order is created and sent to the supplier.

Each of these handoffs is a queue. If the item number is missing from the slip or if the purchasing department is in a meeting, the order creation process is put on hold. According to the study “Managing Indirect Purchasing” by HTWK Leipzig, processing an order takes an average of 38 minutes at the reference company, and only 15% of companies have fully digitized, integrated processes.

Key Fact: In many companies, when a machine breaks down, it is not the delivery time of the replacement part that determines the downtime, but rather the time between identifying the need and the supplier receiving the order.

Which systems interact in spare parts procurement

Typically, four systems work together in spare parts procurement: maintenance software, ERP, a procurement platform, and, if applicable, automated dispensing machines. None of them covers everything on its own. The key is that they are interconnected.

For companies that currently place orders on paper slips, this means: The quickest solution is usually not new maintenance software, but a digital ordering process integrated with the existing ERP system. With the OCI Punchout integration, the ERP system directly imports the shopping cart from the procurement platform as a purchase requisition.

Three types of replacement parts, three procurement channels

Not every spare part requires the same procurement route. By dividing spare parts into three groups based on criticality and availability, you can determine the fastest route for each group.

The majority of orders fall into the middle category. It is precisely these parts that often end up on the order form today, even though they could be ordered in just a few clicks from a supplier like Würth, Hoffmann, Festo, or RS Components.

Tip: Don’t classify spare parts by price, but rather by how long a machine would be out of service without that part. A 20-euro sensor for a bottleneck machine belongs in the warehouse; a 300-euro tool with next-day delivery belongs in the catalog.

5 Steps to Digital Spare Parts Procurement

Spare parts procurement goes digital in five steps: classify parts, connect suppliers, define approval rules, order at the point of need, and integrate with the ERP system. Maintenance and purchasing can complete the first two steps together in just a few days.

1. Classify spare parts

Divide the spare parts ordered over the past twelve months into three groups: stock parts, catalog parts, and special parts. Use orders from the ERP system and the maintenance department’s experience as a basis. The result will show what percentage of orders are currently processed manually via paper slips, even though they could be ordered from a catalog.

2. Integrate Suppliers with Catalogs

Connect suppliers of catalog parts to a procurement platform using your terms and conditions, either as a catalog or via punchout to the supplier’s online store. Suppliers of special parts, such as machine manufacturers, can also be set up as separate suppliers, provided they offer a catalog or punchout. Our guide on Optimizing the Procurement Process.

3. Define Approval Rules for Maintenance

Set a separate spending limit for the Maintenance cost center, below which catalog orders are processed without approval. For orders above this threshold, designate a substitute so that, in the event of an issue, you don’t have to wait for an absent person. Our article on the approval workflow in purchasing.

4. Order at the point of need

Orders are placed right where the need arises: in the workshop, at the shelf, or on the production line. Barcode labels on shelf compartments make this particularly easy. A scanner captures the items, and the order is created without having to type anything. Our article on smart procurement processes in MRO. Consumable parts can also be made available via dispensing machines on the production line.

5. Integrate with ERP and Measure Key Metrics

Connect the procurement platform to the ERP system so that purchase orders are received with cost centers and general ledger accounts, and invoices are automatically assigned. Then measure four key performance indicators:

• Time from demand to placing an order with the supplier: the most important metric for downtime.
• Percentage of catalog orders: indicates whether the new process is being used.
• Percentage of free-text orders: indicates which parts are not yet listed in any catalog.
• Number of rush orders: indicates whether stock parts are classified correctly.

What a spare parts order really costs

For MRO parts, the cost of the ordering process often exceeds the value of the part ordered. According to surveys, a manually processed order costs around 146 euros, while a digitally processed order costs around 86 euros. For a gasket costing five euros, the ordering process is thus many times more expensive than the part itself.

The second, usually larger cost component is downtime. It cannot be quantified with a flat rate because it depends on the equipment, shift schedule, and delivery dates. Our article on process costs per order.

How simple system supports maintenance

simple system is a neutral procurement platform for indirect purchasing that handles the ordering process for catalog and special parts and integrates with your ERP system. Maintenance planning and spare parts inventory remain within your maintenance software or ERP system.

• MRO suppliers already connected: Over 1,000 suppliers are on the platform, including Würth, Hoffmann, Festo, Sonepar, and RS Components. The supplier overview shows a selection of them.
• Your own suppliers with your own terms: Framework agreements are mapped 1:1. simple system connects any missing suppliers.
• Ordering via barcode: Labels from the platform are placed on the shelf; a scanner adds the items to the shopping cart. Depending on user permissions, this generates a purchase requisition or a direct purchase order in SAP.
• Automated dispensing systems and external ordering systems: Withdrawals from connected dispensing systems—such as GARANT Tool24 from Hoffmann—are automatically consolidated in simple system, with cost centers and approval rules specific to each system.
• ERP integration: via OCI to SAP, Microsoft Dynamics, and other systems.
• Approvals based on value thresholds and product groups: also separately for maintenance.

Checklist: Is your spare parts procurement downtime-proof?

• Are your spare parts categorized into stock parts, catalog parts, and special parts?
• Do critical stock parts have a minimum stock level with automatic reordering?
• Can the maintenance department order catalog parts on its own without going through Purchasing?
• Is there a value threshold below which spare part orders can be placed without approval?
• Is a designated representative assigned for each approval level?
• Do orders arrive in the ERP system with a cost center and general ledger account?
• Do you know the lead time from when a need arises until the order is placed with the supplier?

If you checked fewer than four boxes: In the event of a disruption, you’ll lose valuable time before the supplier even knows about your need.

Conclusion: Downtime begins before the order is placed

MRO parts keep production running, and when it comes to procuring replacement parts, most of the time is lost before a supplier even learns of the order. Classifying spare parts by criticality, allowing catalog parts to be ordered directly from maintenance, and designing approval processes around incidents shortens this very process. Maintenance software, ERP, and procurement platforms do not need to be replaced for this—they just need to be integrated.

FAQ: Frequently Asked Questions About MRO Parts and Spare Parts Procurement