Final answer:
Cotter pins and lubricants used irregularly in a production process are classified as indirect materials. These are necessary for the manufacturing process but cannot be directly traced to a specific product, and are included in manufacturing overhead costs.
Step-by-step explanation:
The cotter pins and lubricants used irregularly in a production process are classified as indirect materials. These are items that are used in the manufacturing process but are not directly traceable to specific units of product, or not significant enough in cost to justify being traced to specific products. Unlike direct materials, which are major components of a product, indirect materials are supportive materials that may be consumed as part of the production process but are not a part of the end product themselves.
Accounting for these materials usually involves including them as part of the manufacturing overhead costs. In cost accounting, manufacturing overhead costs, which include indirect materials, are allocated to products based on a pre-determined overhead rate. This ensures that every product shares a portion of the indirect costs, reflecting the use of resources such as cotter pins and lubricants that, while they may not be used consistently, are nonetheless essential to the production process.