Materials Management System | 3 Control Points and MRP Boundaries

Inventory management systems, MRP, order and purchasing management. You already know the vocabulary. And yet you have started researching materials management systems, most likely because you cannot yet pin down which part of your own materials process is missing. Materials management is the day-to-day practice that runs from receiving raw materials and parts, through issuing them to the line, to recording what was actually consumed. This article maps the scope of a materials management system into three control points, then works through the boundaries with MRP, purchasing management and inventory management, the limits of running everything in Excel, and the issues that are specific to a plant in Thailand.

What a Materials Management System Is \| The Scope Is Not Only Raw Materials and Parts

Start by aligning the vocabulary. If the definition is left fuzzy while an internal discussion proceeds, every participant carries a different idea of how far the system should reach, and the specification never settles when the time comes to request quotations.

Materials management means keeping supply intact, not counting boxes

Materials management is generally defined as the whole set of activities that manage and maintain supply so that the materials needed for production are available in the right quantity, at the right time, and in the right place. What matters in that definition is the subject of the sentence. The subject is not the goods themselves, it is the activity of maintaining supply.

In other words, materials management is not simply the job of counting how many items sit in the warehouse. It is the full set of control actions that keep the plant in a state where the required materials are on hand, in the required quantity, at the required moment, in the required location. Counting is only one means to that end. Receiving, storing, issuing and recording what was consumed are all inside the scope.

Review your own plant through that lens and a pattern usually appears. In many factories only the counting has been systemised, while receiving and issue, the steps immediately before and after it, still run on paper and spreadsheets. The motivation to look at a materials management system almost always comes from those two gaps on either side of the count.

Materials include far more than raw materials and parts

The second thing to settle at the definition stage is what counts as a material. The scope of materials management covers not only raw materials and parts but also indirect materials such as tools, maintenance parts for equipment, packaging materials and office supplies.

On the shop floor, everyone recognises raw materials and major parts as materials. Tools and maintenance spares, on the other hand, tend to be treated separately as consumables or spare parts, and end up managed inside one person’s head or in a standalone spreadsheet. Packaging materials follow the same pattern, and it is not unusual for the shipping department to keep its own private list.

Looked at through the question of what stops production, that difference in treatment is not rational. A missing major part stops the line, but running out of packaging material stops shipment just as effectively, and a missing replacement maintenance part can delay equipment recovery by several days. If the definition is the activity of maintaining supply, all of these belong on the same footing.

When you evaluate a materials management system, decide early how wide the item scope will be. Leave it vague and the result is a half-finished state where only major parts end up in the system while indirect materials stay under individual control exactly as before.

What the system produces is a record of physical movement

Putting that together, the role of a materials management system can be restated as follows. Materials arrive from outside the company, are stored inside it, are issued into production, and disappear as part of a finished product. The job is to record that flow and to keep the plant in a state where it can answer, at any moment, where an item is and how much of it remains.

It is not a planning function, not a purchase order issuing function, and not a costing function. Producing the real data that those functions depend on to work correctly is the essential work of a materials management system. Share that positioning at the start and the boundaries covered in the next section become far easier to draw.

Why Materials Management Gets Blurry \| Boundaries with MRP, Purchasing and Inventory Management

The reason an internal discussion about needing a materials management system stalls is that too many adjacent terms are in play. MRP, purchasing management, order management, inventory management. All of them relate to materials, and their functions genuinely overlap in places. What follows accepts the overlap and instead identifies where the centre of gravity of each one sits.

Difference from MRP \| MRP is the plan, materials management is the practice

MRP, material requirements planning, is the mechanism that calculates what should be ordered or manufactured, when, and in what quantity. Its input data is generally described as three things, MPS (the master production schedule), BOM (the bill of materials) and inventory information.

The arithmetic itself is not difficult. Suppose there is a plan to build 100 units of product A, and the BOM says part X is required at 2 pieces per unit. The gross requirement for part X is then 200 pieces. Subtract 50 pieces of on-hand inventory and 30 pieces already on order, and the net requirement is 120 pieces. Working backwards from lead time to decide when those 120 pieces must be ordered is MRP’s job.

The point worth pausing on is where the numbers used in that calculation come from, specifically the 50 pieces on hand and the 30 pieces on order. MRP does not generate those figures itself. They are the accumulated result of goods received, put away and issued on the shop floor. Materials management therefore sits upstream of MRP, not downstream of it. It is the side that creates MRP’s input data.

Consistent with that, the biggest challenge in MRP is usually described as master data accuracy, and recording actual results on paper or in Excel is noted as making transcription errors and time lags hard to avoid, which puts a ceiling on feedback accuracy. The formula can be perfectly correct, but if the inventory figure entering it does not match reality, the order quantity coming out will be wrong every time. The relationship between MRP calculation logic and master data accuracy is covered in detail in what actually stops an MRP system is master data freshness, not the calculation, which is worth reading alongside this article if you are implementing or tuning MRP.

Stated in one line, the boundary is this. MRP is the planning side that decides what to procure and when. Materials management is the practical side that takes the resulting instruction, moves the physical goods, and records what happened. Both look at the same inventory number, but their roles are entirely different.

Difference from purchasing and order management \| The transaction or the physical goods

Purchasing management and order management centre on the processing of the order itself. Supplier selection, obtaining and comparing quotations, issuing the purchase order, receiving the acknowledgement, tracking delivery date replies, acceptance inspection and payment processing all sit inside that scope.

Where it overlaps with materials management is around open order visibility and expected arrivals. The centre of gravity is different, though. Purchasing management deals with the order as a transaction. Materials management deals with the physical goods that arrived. If the order data says 10 pieces are due but only 9 actually turn up, the materials management record has to say 9. Closing that gap is the receiving verification step described later in this article.

The flow of the ordering process itself, and what to look at when selecting a purchasing system, are set out in how to choose an order and purchasing management system and where it meets purchasing and MRP. If you would rather start from the ordering side, use that as your entry point. This article stays with what happens after the order is placed, namely receiving, storage and issue.

Difference from inventory management \| The breadth of what is covered

Inventory management is a broader concept than materials management. It covers all the inventory a company holds, including not only raw materials and parts but also work in progress, finished goods, and in some cases items already shipped but not yet accepted by the customer.

Materials management, by contrast, narrows the scope to what has not yet entered production, which means raw materials, parts and indirect materials. How many finished units sit in the warehouse is not the central concern of materials management.

That distinction feeds directly into system selection. A company whose problem is finished goods turnover and shipping lead time needs something different from a company where parts shortages and excess stock are happening at the same time. The former needs an inventory management system, the latter needs a solution with depth in materials management functions. If both are painful, you have to decide which one to fix first.

The four domains side by side

Here are the boundaries in table form. The level of detail is deliberately set so that the table can be used as is when building shared understanding internally.

What the table is meant to convey is not that materials management ranks below the other three. The relationship is the opposite. The accuracy of the answers the other three domains produce can never exceed the accuracy of the records that materials management creates.

Three Structural Problems in Excel-Based Materials Management

In a great many Japanese-owned plants, materials management still runs on Excel and paper. This is not an argument that Excel is bad. With a limited number of part numbers, a stable person in the role and a single site, Excel works perfectly well. Problems appear when those preconditions break.

What follows organises the problems that typically arise when materials management is run on spreadsheets and paper into three categories. None of them is caused by a lack of effort from the people doing the job. They are structural consequences of the operating method.

Problem 1 \| Key-person dependency, where locations and quantities live in a veteran’s head

Where materials management runs on Excel and paper, dependency on a single person who is the only one who understands the situation is a common outcome. In small and medium manufacturers using spreadsheet-based inventory control, the same issue is described in terms of storage locations and quantities that only a veteran employee really knows.

Key-person dependency cannot be detected by looking inside the Excel file. The file shows part numbers and quantities in neat columns and appears readable by anyone. In practice, though, the corrections exist only in one person’s head. This part number is not actually on shelf A, it is in the temporary staging area. This quantity does not yet include last week’s delivery. A human being is bridging the gap between the file and reality from memory.

The dangerous property of this state is that nothing surfaces while conditions are normal. As long as that person comes to work and does what they always do, materials are supplied correctly. The problem appears when they take leave, transfer to another role or resign. At a plant in Thailand, staff turnover happens more readily than in Japan, and each occurrence brings handover cost and a slow ramp-up for the replacement.

There is also a less visible cost. The person concerned finds it hard to take time off, and their working hours fill up with searching for materials and answering queries, leaving no capacity for improvement work such as reviewing order parameters or reducing stock levels.

Problem 2 \| Transcription errors, driven by long part numbers and similar names

Paper and spreadsheet operation makes transcription errors difficult to avoid. Typical examples described include copying a part number with many digits incorrectly onto a purchase order, and ordering the wrong material because two items had similar names.

Neither example is a problem of individual attention. Both are problems of how the data is held. If the part number scheme runs beyond ten digits, human beings will misconvey it at some non-zero rate. If similarly named materials sit next to each other in a list, they will be mixed up at some non-zero rate. Reminders and double checks reduce the rate. They do not take it to zero.

The awkward property of a transcription error is that it is invisible at the moment it occurs. If a part number is ordered with one digit wrong, the mistake usually surfaces when a different material arrives, or when the material that was needed does not. The longer the lead time from order to arrival, the later the discovery. For a plant in Thailand importing parts from Japan, that delay is measured in weeks.

Systemise the process so that transcription is no longer required and the rate approaches zero. Read part numbers with barcodes or QR codes, and carry order data straight through into receiving data, and the situation where a person copies a part number by hand simply disappears.

Problem 3 \| Inventory discrepancy, where the data and the physical stock disagree

The third problem is inventory discrepancy, the state where the quantity in the data does not match the quantity physically present. It is described as a common outcome of spreadsheet-based operation.

Discrepancies arise through several routes. The issue is not recorded at the time of pick. It is recorded on paper but the Excel entry happens days later and is forgotten. A defective item is scrapped without the record being updated. A small quantity is taken out for a trial or a repair and never logged.

The most typical route of all is the double-entry structure where a note is written on paper and an administrator types it into Excel later. In small and medium manufacturers using spreadsheet-based inventory control, this pattern of writing a note on paper and having the office enter it into Excel afterwards is identified as a core problem. In this method, the data is guaranteed to be older than reality for the whole interval between the note and the entry. It also adds three further error routes, misreading the note, losing the note, and skipping the entry.

Once discrepancies pass a certain threshold, the shop floor stops trusting the inventory data. Data that is not trusted stops being used for ordering decisions, and the behaviour that takes hold instead is ordering extra just in case. Plants where excess stock and shortages occur simultaneously have very often travelled this exact route.

How to size the loss \| Work with a model case, not borrowed numbers

When the cost of Excel operation is discussed internally, someone always asks for it in money. The caution here is that most of the figures circulating as other companies’ results are not measured data, they are assumptions used for illustration.

As a model case commonly used in the industry, for example, a loss estimate may be built on premises such as 5 hours per month spent searching for materials, excess stock worth 150 man-yen (1 man-yen is 10,000 yen, so roughly 1.5 million yen), and 10 production schedule adjustments per year caused by shortages. These are assumptions for the sake of explanation, not measured data from a specific company. If you quote them in an internal approval document, state explicitly that they are a model case.

So how do you produce your own numbers. In practice the fastest route is to measure three things for one week only. First, the total time spent walking the floor looking for materials. Second, the number of occasions where Excel and the physical stock disagreed, and the size of the difference. Third, the number of times the production schedule was rearranged because of a shortage or a wait for materials.

All three can be measured with pen and paper, without any new mechanism. And once measured, they become the baseline for evaluating the effect of the system after implementation. Skip that measurement and go straight to comparing quotations, and the discussion turns into a comparison of prices with no way to judge whether the investment is justified.

The Three Control Points a Materials Management System Solves

This is the core of the article. What you should expect from a materials management system organises neatly into three control points. The three connect in sequence, and if an earlier one breaks down, the later ones cannot stand.

Point 1 \| Receiving verification, matching order data against physical goods

The first point is receiving verification, the act of checking what actually arrived and in what quantity against the order data, and recording any difference on the spot.

In an operation where someone signs the paper delivery note and the goods are carried into the warehouse, this check is routinely skipped. The delivery note says 10, so the data is updated as if 10 arrived. In reality, only 9 may be present, a wrong part number may be mixed in, or some units may have visible damage.

Perform receiving verification in the system and three things happen at once. First, the difference between order data and actual receipt becomes visible at the moment of arrival. Second, that difference reaches the purchasing team immediately, so chasing the supplier or placing a top-up order happens sooner. Third, the initial value of the inventory data is registered in a state that matches the physical goods.

The third one matters most. A discrepancy that enters at the door stays in the data from then on. If the data matches reality at the point of receipt, every later discrepancy can be narrowed down to a missing issue record. Receiving verification is the first point to secure, if only because it makes cause isolation possible.

At a plant in Thailand, receiving verification carries an additional meaning. Imported materials come with several documents, the invoice, the packing list and customs paperwork, and the quantity unit on those documents sometimes differs from the purchase order. Without a mechanism to confirm at arrival that the documented quantity and the physical quantity agree, the gap is discovered for the first time at a stock count weeks after customs clearance.

Point 2 \| Storage and issue, keeping location and pick records

The second point is storage and issue. It centres on location management, which records where something was put, and issue management, which records who took out what, how much, and when.

Without location management, the plant ends up in the state where stock exists but cannot be found. The data says available, the floor cannot find it, an extra order goes out, and the original items turn up later. Repeat that cycle and it becomes one of the main drivers of excess stock. Location management is the direct countermeasure to the search-time problem raised in the previous section.

Issue records deliver the largest effect against inventory discrepancy, and they also place the heaviest burden on the shop floor. Operators have to touch a terminal every time they take materials out. If the operation breaks down here, records simply do not accumulate even after the system is live, and the discrepancy problem is never resolved.

In practice, the key to adoption is to align the unit of the issue record with the way the floor actually moves. Rather than recording every single piece, record by box or by production order. Make the record complete with a single barcode scan. Put the recording point physically on the path along which materials are taken out. Decide this design before implementation, or operation will drift back to the same old structure of entering everything later because doing it now is too much trouble.

Point 3 \| Usage results against BOM consumption, building the input MRP depends on

The third point is reconciling actual usage against the theoretical consumption implied by the BOM. It is the most frequently overlooked of the three, and the one with the largest effect.

The idea is simple. Build 100 units of product A where the BOM says part X is needed at 2 pieces per unit, and theoretical consumption is 200 pieces. If the actual issue record shows 210 pieces, a difference of 10 pieces exists. That difference means rework caused by defects, an allowance consumed during setup, an error in the records, or a BOM that no longer matches reality.

Run that reconciliation continuously and two results follow. One is that actual yield becomes visible as a number. The other is that BOM accuracy improves. BOMs are created at the design stage, and it is common for later process improvements and part substitutions never to be reflected in them. Reviewing the gap against actuals on a regular cycle is how you notice a BOM going stale.

Both of those results feed straight into MRP accuracy. As described earlier, MRP takes a plan to build 100 units of product A, calculates a gross requirement of 200 pieces from the BOM, and subtracts 50 pieces on hand and 30 pieces on order to arrive at a net requirement of 120 pieces. If the on-hand figure used in that calculation does not match the physical stock, the net requirement is wrong. If the BOM figure of 2 pieces per unit differs from reality, it is wrong for that reason too.

The biggest challenge in MRP is generally described as master data accuracy. The people producing that master data every day, though, are the materials management team on the floor. That is why, when a customer asks us to improve MRP accuracy, the first thing we look at is the state of their receiving and issue records. Making the calculation logic more sophisticated does not improve the output while the input disagrees with the physical stock.

The three points cannot be separated

Finally, note how the three points relate. If receiving verification is weak, the initial value of the inventory data is wrong. Record issues on top of a wrong initial value and the remaining quantity still will not agree. And if the remaining quantity does not agree, reconciling usage against the BOM cannot tell you whether a difference comes from a missing record or from yield.

For that reason, even when a materials management system is introduced in stages, starting from receiving is the rational sequence. Begin with BOM reconciliation and the analysis has no foundation, because the underlying inventory data cannot be trusted.

Materials Management Challenges Specific to Thai Plants

From here the discussion moves to conditions on the ground in Thailand. Compared with a plant in Japan, materials management at a Thai site carries its own particular difficulties.

Locally sourced and imported parts share a single material master

Thailand’s local sourcing base for components is regarded as mature compared with other ASEAN countries, which makes a high local content ratio comparatively achievable. It is the result of supply chains built up over decades around the local production of vehicle manufacturers such as Toyota, Honda and Isuzu. That is a significant advantage for a Thai operation.

At the same time, the advantage creates a problem specific to materials management practice. In most Japanese-owned plants, parts that can be sourced locally coexist with parts that must be imported from Japan for reasons of quality or specification. And both sit in the same material master, registered in the same format, line after line.

What follows is our own practitioner view. Sitting in the same master does not make them the same thing. Locally sourced and imported parts differ fundamentally in character. Lead times of days versus weeks. Units of PCS versus BOX or KG. Currencies of THB versus JPY or USD. With those three varying inside a single table, reorder points and safety stock cannot be set on a single logic.

Even so, Excel-based operations tend to treat both under the same rules. Apply a simple rule such as reorder when stock falls below the reorder point to every item, and imported parts with long lead times will run out, guaranteed. Set safety stock high enough to protect the imported parts, and you will carry unnecessary stock of the locally sourced ones.

Three sources of variation, lead time, unit and currency

Look at each one more concretely. First, lead time. A part that can be covered in a few days to two weeks from a local supplier takes several weeks by sea freight when imported from Japan, and longer again depending on customs. If that difference is not held correctly as a lead time attribute in the material master, the order timing MRP calculates translates directly into a shortage.

Second, units. A part ordered in PCS from a local supplier may only be available in minimum packaging units of BOX when imported, or may be traded by weight. When the ordering unit, the issue unit and the stock unit disagree, every conversion creates a rounding remainder, and remainders are a breeding ground for inventory discrepancies.

Third, currency. With THB-denominated, JPY-denominated and USD-denominated items mixed together, the monetary valuation of materials moves with the exchange rate. In practice, unless the mechanism lets you consider quantity control and value control separately, the month-end inventory value will not track the movement in quantities, and explaining the cause takes time.

The direction of the countermeasure is clear. Hold procurement category, lead time, the conversion between ordering unit and stock unit, and transaction currency as explicit attributes in the material master. Then separate the logic for reorder point and safety stock by procurement category. When you systemise, decide this attribute design first. Adding it later means revisiting every record in the master.

What the 2026 economic environment means for materials management

On the Thai economy in 2026, private-sector think tanks and financial institutions have reported a run of downward revisions to their 2026 GDP growth forecasts, to roughly 1.8% to 2.0%. The July to September quarter of 2025 is also reported to have turned negative, at an annualised 2.24% contraction quarter on quarter. Please note that these are private-sector forecast revisions as reported, not official outlooks from bodies such as the IMF.

What that environment means for materials management is offered here as our own analysis. When demand visibility is poor, production plans move more. When plans move, the quantity and timing of the materials required move with them. If inventory data is stale at that moment, material procurement cannot keep up with the plan change, and either a shortage or excess stock will follow without fail.

The need to detect movements in procurement cost early also rises. When raw material prices or exchange rates move, whether you can see which parts are sitting in stock, in what quantity, at what unit cost, on a cycle shorter than monthly, decides how quickly you can react on price revisions or alternative part studies. If unit cost and quantity are captured at receipt and consumption is captured at issue, that visibility becomes a property of the mechanism. With paper and after-the-fact Excel entry, the earliest you can see it is next month.

In a strong economy, a little excess stock and a little delay in visibility are absorbed by revenue growth. When the outlook is uncertain, there is less room to absorb them, and the accuracy of materials management shows up directly in cash flow. If there is a reason to review materials management in 2026, we believe this is the most practical one.

Sharing information with the head office in Japan

One more practical issue specific to Thai operations is information sharing with the parent company in Japan. It is not unusual for imported parts to be arranged by the purchasing department at head office while the local site simply waits for arrival. In that structure, if local inventory actuals are not visible to head office, procurement decisions there depend on emailed reports from the site.

If each report means the site aggregating an Excel file and head office transcribing it into a different one, then the transcription errors and key-person dependency described earlier are simply happening a second time, this time between sites. When evaluating a materials management system, include not only efficiency within the local site but also whether head office can see the same data at the same freshness.

How to Choose a Materials Management System and How to Roll It Out

Finally, here is how to think about the evaluation itself.

Start from identifying what is missing

A common failure in selecting a materials management system is starting from a comparison of feature lists. Every product on the market offers receiving, stock, issue and stock counting, so lining the features up side by side reveals no difference.

The starting point should be identifying which part of your own materials management is missing. Following the structure used above, is receiving verification missing, are location and issue records missing, or is reconciliation of usage against the BOM missing. Which of the three hurts most determines which functions to prioritise.

The material for that judgement is the three measurements mentioned in the Excel section. If search time is large, location management comes first. If inventory discrepancy is large, receiving and issue records come first. If shortages and schedule adjustments are frequent, BOM reconciliation and MRP integration come first.

Separate the roles first, then start small

The next decision is the division of responsibility with existing systems. If you already run an inventory management system or a production management system, decide up front which one owns the materials management functions, or you will end up with the same data living in two places.

The approach we recommend is to narrow the recording of physical movement down to one place. Consolidate receiving, storage, issue and stock count records in a single system, and put MRP and costing on the receiving end of that data. With that arrangement in place, adding MRP later or replacing the inventory management system leaves the physical movement data untouched.

On scope, we recommend starting small. Concretely, begin with the materials used by one warehouse or one product line, and run receiving and issue records for those only. Operate for a few weeks, confirm that records actually accumulate and how heavy the burden on the floor really is, and only then widen the item scope and the number of sites.

Start with every item at every site and master data preparation alone will take months, during which enthusiasm on the floor cools. And if the recording rules turn out not to fit the way the floor works, the blast radius of the correction is far too large.

How to think about cost

This article does not quote a specific price range. The label materials management system covers a very wide span of scope, from simple goods-in and goods-out recording through to a module inside a full production management suite, so we are not at a point where a reliable market range can be stated. If you need a sense of pricing, obtain several actual quotations and compare them.

That said, the structure of the cost is common to all of them. The investment includes not only the initial licence or development fee but also the effort of preparing master data, floor devices such as handheld terminals and label printers, integration development with existing systems, training and adoption support, and maintenance cost after go-live. Master data preparation in particular can be the single largest line item at a plant with a large number of part numbers, so always confirm whether it is included in the quotation.

For a way of breaking down cost that extends to inventory management systems as well, comparing factory inventory management systems and thinking about cost in five layers sets out a method for estimating cost layer by layer along with how to handle inventory discrepancy. When you move to the budgeting stage, using that as your framework is the practical choice.

The operating rules that make it stick

The last thing that determines whether an implementation succeeds is the operating rules. More than any technical setting, we recommend deciding the following three items before go-live.

First, document the timing of each record and the person responsible for it, process by process. If who records what and when is left ambiguous, records start disappearing on the busy days. Second, decide the correction procedure for when a missing record is discovered. Without a correction procedure, the floor will leave errors unreported. Third, decide the frequency of stock counts and the procedure for tracing the cause when a discrepancy appears.

Go live without deciding these and within six months you are back to the same place as before, with everyone saying the numbers in the system cannot be trusted. Put the other way round, once those three are settled, differences in system features stop being a major issue.

A Checklist for Deciding Whether This Applies to You

These are the confirmation items for judging whether evaluating a materials management system makes sense for your plant. They are written at a level of detail that lets you check them while walking the floor.

• Can someone other than the person in charge identify the location and exact quantity of a material from documentation alone
• Are order data and actual received quantities reconciled on the day of arrival
• Are issue records created at the moment the goods are physically taken, rather than entered in a batch later
• Are material locations recorded so that items can be retrieved without a search
• Are indirect materials, tools, maintenance parts and packaging materials managed by the same mechanism
• Is actual usage reconciled against theoretical BOM consumption on a regular cycle
• Does the material master carry procurement category, lead time, unit conversion and transaction currency as attributes
• Can you state how many times in the past month the inventory data disagreed with the physical stock
• Can you state how many times in the past month the production schedule was rearranged due to a material shortage or delay
• Can the head office in Japan see local material inventory in the same data at the same freshness

If you cannot confidently answer yes to the first three, there is a practical reason to evaluate a materials management system. Conversely, if you cannot yet answer the counts in the last two items and you go out for quotations anyway, you will be comparing prices with no baseline against which to measure the effect.

Frequently Asked Questions

What is a materials management system

It is a mechanism that supports the management work of keeping production materials available in the right quantity, at the right time, and in the right place. Its scope covers not only raw materials and parts but also indirect materials such as tools, equipment maintenance parts, packaging materials and office supplies. Functionally, it centres on receiving verification that matches order data against physical arrivals, records of storage location and issue, and reconciliation of actual usage against theoretical BOM consumption.

What is the difference between materials management and inventory management

The scope differs. Inventory management handles all inventory a company holds, from raw materials through work in progress to finished goods, whereas materials management narrows the scope to raw materials, parts and indirect materials that have not yet entered production. There is also a difference in nature, in that materials management is not only counting but the whole activity of maintaining supply, meaning receiving, storing, issuing and recording what was consumed. If your problem is finished goods turnover, start from inventory management. If parts shortages and excess stock are occurring at the same time, starting from materials management is the practical sequence.

What is the difference between materials management and MRP

MRP is a planning-side mechanism that calculates what to procure, when, and in what quantity, taking MPS, BOM and inventory information as its input data. Materials management is the practical side that creates the inventory information and usage results used in that calculation. For example, when MRP calculates a gross requirement of 200 pieces of part X for 100 units of product A, and subtracts 50 pieces on hand and 30 pieces on order to produce a net requirement of 120 pieces, it is materials management that produced the on-hand and on-order figures. The biggest challenge in MRP is generally described as master data accuracy, which means the accuracy of materials management records sets the ceiling on the accuracy of MRP output.

How can key-person dependency in materials management be resolved

The starting point is externalising the corrections that live inside one person’s head, turning them into records. Concretely, there are two moves. Record material locations so that storage positions can be identified from documentation, and record issues at the moment they happen so that no mental correction of the remaining quantity is required. Key-person dependency cannot be found by inspecting the Excel file, and only surfaces when the person concerned is absent. In an environment where staff turnover is common, the externalisation has to be done while conditions are still normal.

How far can materials management in Excel be sustained

With a limited number of part numbers, a stable person in the role and a single site, Excel works perfectly well. The limits appear when certain states become permanent, such as transcription errors caused by long part numbers, storage locations and quantities known only to a veteran, a double-entry structure where notes on paper are typed in later, and inventory data that does not match the physical stock. These are structural consequences of the operating method rather than a lack of individual effort, and reminders or double checks can lower the rate but cannot eliminate them.

What should we watch out for when implementing a materials management system in Thailand

The most practical issue is handling locally sourced parts and parts imported from Japan inside the same material master. Thailand’s local sourcing base is regarded as mature compared with other ASEAN countries, yet the two categories differ in lead time, ordering unit and transaction currency. Apply the same ordering rule to every item and you will either run short on imported parts or carry unnecessary stock of locally sourced ones. Hold procurement category, lead time, unit conversion and currency as attributes in the material master, and separate the logic for reorder point and safety stock by category. This attribute design should be decided before implementation, because adding it later means revisiting every record in the master.

Summary

Here are the points to hold on to when evaluating a materials management system.

• Materials management is the whole activity of maintaining supply in the right quantity, at the right time, and in the right place, and its scope is described as covering not only raw materials and parts but also indirect materials such as tools, maintenance parts, packaging materials and office supplies
• MRP is planning, purchasing management is order processing, and inventory management centres on all inventory including finished goods, while materials management is the practical side that creates the underlying real data for all three
• The three problems that typically arise in Excel operation are key-person dependency where locations and quantities live in one head, transcription errors driven by long part numbers and similar names, and inventory discrepancy where data and physical stock disagree
• The scope of a materials management system organises into three control points, receiving verification, records of storage and issue, and reconciliation of usage results against BOM consumption
• MRP derives a net requirement of 120 pieces by taking a gross requirement of 200 pieces for 100 units of product A and subtracting 50 pieces on hand and 30 pieces on order, but the accuracy of that on-hand figure is created by materials management records
• At a Thai plant, locally sourced and imported parts share one material master and tend to be managed with differing lead times, units and currencies. Holding procurement category as a master attribute is the starting point of the countermeasure
• Private-sector forecasts for the Thai economy in 2026 have been revised down to roughly 1.8% to 2.0% GDP growth as reported, which puts more weight on materials management accurate enough to catch movements in procurement cost early
• Starting from receiving and widening the scope from there is the rational rollout, and the timing and ownership of records, the correction procedure, and the stock count and discrepancy tracing procedure should all be decided beforehand

The first thing to do is neither comparing products nor collecting quotations. It is to establish where your own materials management is missing, using three measurements, search time, the number of inventory discrepancies, and the number of schedule adjustments caused by shortages. Proceed without those numbers and the evaluation collapses into a comparison of feature lists with no basis for a decision.

TOMAS TECH supports digital transformation on the shop floor for Japanese manufacturers operating in Thailand, including our PEGASUS production management system. On materials management we are happy to start from the questions that come before product selection, such as whether an additional system is needed at all and how responsibilities should be split with an existing production management system. Information gathering before any decision is perfectly welcome, so please get in touch through our contact page.

References

• TS-BASE – what materials management covers and the problems with running it in Excel
• SMART CRAFT – how MRP works and how the requirement calculation is built up
• asakura-toyama.jp – key-person dependency and double entry in inventory control at small and medium manufacturers
• Digima – manufacturing in Thailand and the local sourcing base
• allied-thai.co.jp – the Thai economic outlook for 2026 and downward revisions in private-sector forecasts