Specification of Standard Mechanical Components
Learning Objectives
In this part we will look at some best practices and guidelines for specifying and buying common mechanical components from suppliers. By the end of this section, readers will be able to:
- Understand and describe the process for selecting off the shelf components from suppliers
- Utilize common best practices for identifying the ideal range of values for specifying a component
- Utilize supplier tools to identify parts based on the specification
It is very common in most machine and mechanical design applications that at least some of the components that form the product will be off the shelf components from a supplier. Economies of scale dictate that it is far more economical to purchase standard parts or have customized parts made by a supplier that already has the required manufacturing equipment, expertise, and supply chains established. Thes types of parts are known as COTS or commercial off the shelf components.
COTS of common mechanical products such as gears, bearings, pins, springs, etc., are widely available from various manufacturers and suppliers, and can offer advantages such as lower cost, shorter lead time, higher reliability, and easier maintenance. However, finding and specifying the right off-the-shelf components can be a complex and time-consuming process that involves multiple steps and considerations.
Some of the steps involved in the process of specifying and finding off-the-shelf components are:
- Define the design criteria and constraints for the component, such as size, load, speed, temperature, environment, service life, etc.
- Identify the possible types and categories of components that can meet the design criteria and constraints, such as spur gears, ball bearings, cotter pins, helical springs, etc.
- Search for available products from different manufacturers and suppliers that match the type and category of the component, using online catalogs, databases, websites, etc.
- Compare and evaluate the products based on their specifications, features, ratings, costs, availability, etc., and select the most suitable ones for further analysis.
- Perform detailed calculations and simulations to verify that the selected products can satisfy the design criteria and constraints under the expected operating conditions.
- Check for compatibility and interference issues with other components and parts of the system and make any necessary adjustments or modifications.
- Document the component selection process and results and prepare a bill of materials (BOM) that lists the part numbers, quantities, descriptions, prices, etc., of the selected components.
