Question

This is the case of the threaded ball studs. Forward Motors Corporation makes about 2,000,000 threaded ball studs each year, as shown in Figure 6.1. They currently are machined from hot-rolled AISI 1030 bar stock of diameter D, heat-treated to 70,000 psi ultimate strength, and the ball surface is then ground to the required finish. Tolerances on the ball and threaded portion are 0.002 inch. Other dimensions are held to 0.025 inch. Dependable quality is important.It is desired to reduce the cost of this part and, if possible, reduce the weight. How would you bring about the desired improvement? The diameter of the ball, D is about 1.5 inches.

This is open-ended question and answer will vary from student to student. But to arrive at a plausible desired improvement, the following factors must be considered. Select all that apply. Your report must state how each factor will reduce cost.

Higher production rates
Less waste of metal
Greater strength
Favorable grain orientation

Which of the following process will likely provide the desired improvement? Select the two that best apply. Your report must describe the process will reduce cost relative to the current process.

Machine from hot-rolled steel
Impact extrusion from cold-drawn steel
Investment casting from cold-drawn steel
Direct or indirect extrusion from hot rolled billet
Impression-die forging from cold-drawn steel

Answer 1

In order to reduce costs relative to the current process, two potentially effective methods could be:

Direct or indirect extrusion from hot-rolled billet

Impression-die forging from cold-drawn steel

Utilizing hot-rolled steel in the extrusion process can be cost-effective. Hot-rolled steel is typically more economical than cold-drawn steel, and the extrusion process allows for efficient shaping of the material, potentially reducing overall production costs.

Forging from cold-drawn steel can offer cost advantages due to the initial savings in material costs compared to hot-rolled steel. Additionally, the impression-die forging process allows for precise shaping, ensuring minimal waste and improved material utilization, further contributing to cost reduction.