The instrument plays a crucial role in steel manufacturing because it presents in the majority of products, in which case lacking this instrument would have significant impact on the organisation's output (production lines stop or damaging other machine). Otherwise, the risk of supply is high because there is limitation in supply. Therefore, it is considered as a strategic item in term of Kraljic's portfolio matrix. Procurement manager should form partnership with suppliers to maximise the value.
The following graph illustrates Kraljic's portfolio matrix:

3D-printed parts can replace traditional metal parts. They are also more easily customised to fit customer's needs. This technology is an example of threat of substitute in Porter's Five Forces model.
Substitute goods or services that can be used in place of a company's products or services pose a threat.
Companies that produce goods or services for which there are no close substitutes will have more power to increase prices and lock in favorable terms. When close substitutes are available, customers will have the option to forgo buying a company's product, and a company's power can be weakened.

The following are typical social criteria in procurement:
* Reducing unemployment
* Preventing the use of child labour
* Preventing discrimination on the grounds of race, religion, disability, sex or sexual orientation
* Encouraging good employment practice
* Reducing local unemployment
* Reducing social exclusion
* Promoting training opportunities for the young or disadvantaged
* Encouraging access to work for people with disabilities
Reference:
LO 3, AC 3.2

The buyer won't pay the supplier until next month. This is a liability to the buyer. This amount can be recorded as accrued expense or accounts payable. On the other hand, the supplier has not sent the invoice, so it should be accrued expense.
Both accounts payables and accrued expenses are liabilities. Accounts payable is the total amount of short- term obligations or debt a company has to pay to its creditors for goods or services bought on credit. With accounts payables, the vendor's or supplier's invoices have been received and recorded.
On the other hand, accrued expenses are the total liability that is payable for goods and services that have been consumed by the company or received. However, accrued expenses are those bills in which an invoice or bill has not yet been received. As a result, accrued expenses can sometimes be an estimated amount of what's owed, which is adjusted later to the exact amount, once the invoice has been received.
Conversely, accounts payable should represent the exact amount of the total owed from all of the invoices received.

Overhead variances arise when the actual overhead costs incurred differ from the expected amounts. Managers want to understand the reasons for these differences, and so should consider computing one or more of the overhead variances described below. Each of these variances applies to a different aspect of overhead expenditures. It is not necessary to calculate these variances when a manager cannot influence their outcome.
Fixed Overhead Spending Variance
The fixed overhead spending variance is the difference between the actual fixed overhead expense incurred and the budgeted fixed overhead expense. An unfavorable variance means that actual fixed overhead expenses were greater than anticipated. The formula for this variance is:
Actual fixed overhead - Budgeted fixed overhead = Fixed overhead spending variance The amount of expense related to fixed overhead should (as the name implies) be relatively fixed, and so the fixed overhead spending variance should not theoretically vary much from the budget.
Fixed Overhead Volume Variance
The fixed overhead volume variance is the difference between the amount of fixed overhead actually applied to produced goods based on production volume, and the amount that was budgeted to be applied to produced goods. For example, a company budgets for the allocation of $25,000 of fixed overhead costs to produced goods at the rate of $50 per unit produced, with the expectation that 500 units will be produced. However, the actual number of units produced is 600, so a total of $30,000 of fixed overhead costs are allocated. This creates a fixed overhead volume variance of $5,000.
Variable Overhead Efficiency Variance
The variable overhead efficiency variance is the difference between the actual and budgeted hours worked, which are then applied to the standard variable overhead rate per hour. The formula is:
Standard overhead rate x (Actual hours - Standard hours)
= Variable overhead efficiency variance
A favorable variance means that the actual hours worked were less than the budgeted hours, resulting in the application of the standard overhead rate across fewer hours, resulting in less expense being incurred. However, a favorable variance does not necessarily mean that a company has incurred less actual overhead, it simply means that there was an improvement in the allocation base what was used to apply overhead.
Variable Overhead Spending Variance
The variable overhead spending variance is the difference between the actual and budgeted rates of spending on variable overhead. The variance is used to focus attention on those overhead costs that vary from expectations. The formula is:
Actual hours worked x (Actual overhead rate - standard overhead rate)
= Variable overhead spending variance
A favorable variance means that the actual variable overhead expenses incurred per labor hour were less than expected.
In the study guide, CIPS splits overhead variance into volume and expenditure variance. They can be understood as variable and fixed overhead variance respectively.
Reference:
- CIPS study guide page 59
- What are overhead variances? - AccountingTools
LO 1, AC 1.4