Performing maintenance requires that spare parts need to be carried. This is particularly important where the nature of some equipment means that the parts are not readily available when they are needed. Spares that fall under this category are considered critical spares and are defined as slow-moving spare parts. They generally can be identified as spares that:
- Cause excessive downtime when they fail,
- Are high cost,
- Have long lead times, and
- Are ordered individually.
Failure to hold an optimum level of critical spares exposes the business to risk. Consumables are defined as fast moving spare parts (i.e. nuts, bolts, filters, oil, grease etc.).
Note
For the purposes of a Critical Spares Analysis, all spare parts with an Annualised Failure Rate of 0.5 or higher are considered consumables and should be omitted from the analysis.
A successful critical spares analysis is one that delivers value. Value can be delivered by:
- Ensuring optimum holding of critical spares (balances risk cost of failure with cost of holding the spare part).
- Ensuring critical spares are purchased only when recommended.
- Reducing holding where recommended.
- Ensuring analysis takes account of commonality across equipment types and redundancy (where applicable).
Creating a Spares Analysis
Creating a spares analysis in Orien involves several steps. Let's review these in some more detail.
- Ensure you have an hourly downtime cost associated with your functional location (in this example, we're looking at the articulated dump truck, which has an hourly downtime cost of 10,000).
- Select the Spares Analysis module and then Perform Spares Analysis At This Level.
- Select Edit and then enter the appropriate percentages in the Storage and Maintenance field and the Cost of Money Tied Up field. For this example we've used 2%. Save your changes.
- Select the Input tab. You can either add spares individually (Add button) or from the allocated material from the asset's location (Initialise with Allocated Materials button).
- For this example we're going to use the allocated materials. Select Initialise with Allocated Materials and then the Reload button. You will be presented with a list of allocated materials.
Note
If no materials appear, you'll need to add your spares individually using the Add button.
- Now we can generate results for our Spares Analysis. Select the Results tab, and then the Material you want to analyse. Select the View Charts button.
- There are five different info-graphics that will display the Spares Analysis for your selected Material. (the Summary Chart is shown below; select the other tabs to view the associated charts).
Your spares analysis can produce the following data for export:
- Current holding total impact
- Recommended spares holding
- Recommended year of initial purchase
- Reliability of the system
- Downtime risked cost
- Storage and maintenance costs
- Total impact
- Saving compared to current holding
- Stock change
The process of creating a spares analysis is also demonstrated in the video tutorial below:
Spares Analysis Data Requirements
The key terms displayed during the spares analysis process are detailed below.
| ATTRIBUTE | DESCRIPTION | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Item Description | The name of the material pre-filled from the materials table. | ||||||||||||||
| Expense Element | Pre-filled from the materials table. | ||||||||||||||
| Stock Code | Pre-filled from the materials table. | ||||||||||||||
| Part Number | Pre-filled from the materials table. | ||||||||||||||
| Number of Units Installed |
Specify the number of concurrent installations of this part in equipment that could potentially fail. This includes where this part is used in equipment that is used as a standby or backup.
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| Number Required for Normal Operation |
The number of parts required for normal operation provides the differentiator between those spares installed for the purpose of redundant backups. If Redundancy exists, then this number should differ from no of units installed.
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| Type of Redundancy |
Three options for describing the type of redundancy: Active, on standby or none. Downtime cost is dependent on whether standby exists or not. This field requires manual entry in Orien.
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| Purchase Price | Purchase price of the spare part as advised by the Supplier/Manufacturer. Pre-filled from the Materials Table. | ||||||||||||||
| Normal Purchasing Lead Time | Normal lead-time to acquire the spare part as advised by the Supplier/Manufacturer. Expressed in days. Manual entry in Orien. | ||||||||||||||
| Expedited Lead Time |
Expedited lead-time to acquire the spare part as advised by the Supplier / Manufacturer. If downtime is being incurred, it is possible to expedite the spare part (at a cost). This value cannot be zero.
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| Additional Cost to Expedite | Additional cost to acquire the spare part when an expedited request is made as advised by the Supplier/Manufacturer. If downtime is being incurred, it is possible to expedite the spare part (at a cost). This cost can be significant and should be included. Manual entry in Orien. | ||||||||||||||
| Probability of Item Available for Expediting |
The probability that the spare part can be expedited as advised by the Supplier or Manufacturer.
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| Chance of Repairing the Failed Unit |
A probability rating for what the chance is that the item/part can be repaired? Is it technically feasible to repair the item/part in any way? Orien does NOT considering if it is repaired, or if it is an economical repair, major repair, or normal repair.
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| Repair Lead Time | The time taken to carry out the repair as specified whilst understanding the chance of repairing the failed item. Expressed in days. Manual entry in Orien. | ||||||||||||||
| Estimated Cost of Repair |
The cost to carry out the repair as specified whilst understanding the chance of repairing the failed item. Factors such as labour, cost of materials needed for the repair and location should be considered.
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| Downtime Cost per Hour |
The cost of downtime should failure of part affect operation. If failure of this part does not affect operation, then the cost of downtime is zero.
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| Downtime Delay | The delay before a downtime cost is incurred. This is particularly useful where a buffer exists in the process which allows operations to continue for a period before operations in impacted. Expressed in hours. Manual entry in Orien. | ||||||||||||||
| Annualised Failure Rate | Annualised Failure Rate is the failure rate expected per year. Very simplistically it is the yearly production forecast divided by the MTBF of the spare part. | ||||||||||||||
| Estimated Shape Factor |
The average shape factor for all failure modes associated with a replacement of the spare part. The shape factor (beta) will be specified at the failure mode level in Orien.
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| Current Holding Policy | The current spares holding policy for this spare part. Generally, this is the re-order point specified in the spares catalogue. Manual entry in Orien. | ||||||||||||||
| Current Holding Total Impact | Calculated Value based on the Storage and Maintenance Cost, and the Downtime Risk Cost, included for export purposes. | ||||||||||||||
| Recommended Spares Holding | Calculated Value based on lead time and Impact Costs, included for export purposes. | ||||||||||||||
| Recommended Year of Initial Purchase | Calculated Value based on Lead time and Failure Rate, included for export purposes. | ||||||||||||||
| Reliability of System | Calculated Value based on Failure Rate, lead time, repair percentage, and current holding policy, included for export purposes. | ||||||||||||||
| Downtime Risked Cost | Calculated Value based on lost production, lead time, and expedition, included for export purposes. | ||||||||||||||
| Storage and Maintenance | Calculated Value based on Storage and Maintenance Costs and the number of units, included for export purposes. | ||||||||||||||
| Total Impact | Calculated Value of Downtime Risked Cost, and Storage and Maintenance, included for export purposes. | ||||||||||||||
| Saving Compared to Current Holding | Calculated Value of Holding Impact and Stock values, included for export purposes. | ||||||||||||||
| Stock Change | Calculated Value, included for export purposes. |