Build quality, or the level of material precision, is one of the key aspects considered in the manufacturing process. This is because build quality has a significant impact on ensuring the safety and durability of every component used by consumers.

In this context, materials are required not only to have high strength but also good flexibility to optimize production costs while simplifying manufacturing processes. This is why most manufacturing industries choose aluminum as a primary material.

Fundamentally, aluminum has a relatively low density as well as better heat resistance compared to steel. However, in manufacturing practice, cleaning through sandblasting alone is not sufficient to guarantee material build quality, particularly for aluminum wheels. Therefore, to ensure the material’s hardness after the pretreatment (sandblasting) and coating processes, aluminum wheels must undergo a heating stage using oven curing at temperatures of 200–220 °C.

According to a study by Ir. Margono Sugeng, M.Sc., a lecturer in the Mechanical Engineering Program at Dian Nusantara University (UNDIRA), the mechanical properties of aluminum change due to heat treatment at specific temperatures. Nevertheless, each temperature stage and time interval theoretically produces different levels of hardness at the microstructural level and affects the adhesion of the coating applied to the outer aluminum layer—ultimately influencing the wheel’s build quality.

This study focuses on microhardness testing and metallographic analysis to support observations of microstructural changes after the coating process and oven heating at 210 °C over time variations of 15, 30, and 45 minutes under two conditions. In this research, aluminum wheels were tested under two scenarios: without powder coating and with powder coating.

It is important to note that the powder coating process (or other epoxy-based coatings) applied to aluminum wheels not only serves as an aesthetic enhancement but also functions as an additional protective layer against surface deformation.

After subjecting four samples to heating at different time intervals, both with and without powder coating prior to heating, the results reveal variations in hardness levels across each sample based on metallographic testing and microscopic observations of the material structure.

For aluminum treated with powder coating and subjected to progressively longer oven curing durations, improved hardness levels were observed as follows: 79.67 after 15 minutes, 83.56 after 30 minutes, and the highest hardness of 90.23 after 45 minutes. In contrast, samples without powder coating yielded a hardness value of 80.93. Although this value is higher than that of the 15-minute coated sample, it tends to be more susceptible to material stretching (degradation), which is generally indicated by gradual deformation during wheel usage.

These findings also reinforce long-term durability considerations: even though aluminum wheels have undergone heat treatment, the presence of microscopic pores on the outer layer that are not fully sealed by powder coating may progressively reduce build quality, despite the material theoretically possessing strong hardness characteristics.

Through applied research such as this, the Mechanical Engineering Program at UNDIRA continues to demonstrate its commitment to delivering innovations that are relevant to the needs of modern manufacturing industries. The program offers not only theoretical knowledge but also practical solutions based on field testing and accessible implementation considerations to achieve peak performance across various mechanical systems and components.

For UNDIRA colleagues interested in material engineering, manufacturing processes, and the development of applied research-based technologies, now is the time to join the Mechanical Engineering Program at UNDIRA and become part of a new generation of engineers ready to tackle future industrial challenges.