ANALISIS VARIASI JARAK ANODA KATODA DAN WAKTU PELAPISAN HARDCHROME TERHADAP KEKERASAN DAN KETEBALAN LAPISAN PADA BAJA ST41 YANG DIKERASKAN

THE ANALYSIS OF ANODE-CATHODE DISTANCE VARIATION AND HARDCHROME PLATING TIME ON HARDNESS AND COATING THICKNESS OF HARDENED ST41 STEEL

King pin merupakan salah satu komponen utama pada kendaraan truck yang berbahan baja ST41. Saat dilakukan surve di bengkel Alfian Motor, juga sering dijumpai kerusakan pada sistem kemudi dengan penyebab utama adalah king pin. Dilapangan juga terjadi kelangkaan suku cadang king pin original membuat orang memiliki suku cadang  non original. Kualitas king pin non original sangatlah rendah dengan kekerasan 43.3 HRC dan king pin original dengan kekerasan 64.1 HRC. Rendahnya kualitas king pin non original tentumya dapat ditingkatkan lagi dengan melakukan proses pelapisan hardchrome yang bertujuan untuk mencari pengaruh variasi jarak anoda-katoda dan waktu pelapisan electroplating terhadap kekerasan dan ketebalan hasil lapisan hard chrome.

Pada objek penelitian eksperimental ini digunakan spesimen king pin yang dikeraskan dan diberi lapisan hardchrome dengan variasi jarak anoda-katoda 10, 15, 20 cm dan waktu pelapisan 60, 75, 90 menit. Pengambilan data dapat diperoleh melalui pengukuran nilai kekerasan dan ketebalan lapisan yang dihasilkan menggunakan alat Leeb Hardness Tester dan Coating Thickness Gauge sebagai instrumen penelitian. Selanjutnya data yang dihasilkan dianalisa pengaruh dari variabel bebas terhadap variabel terikat digunakan metode anova untuk mengetahui tingkat signifikansi dari setiap variabel yang digunakan.

Hasil dari penelitian dengan nilai kekerasan & ketebalan tertinggi diperoleh pada variasi jarak anoda-katoda 10 cm dan waktu pelapisan 90 menit dengan nilai kekerasan sebesar 67,68 HRC dan nilai ketebalan sebesar 51,85 µm. Sedangkan nilai kekerasan dan ketebalan terendah diperoleh pada variasi jarak anoda katoda 20 cm dan waktu pelapisan 60 menit dengan nilai kekerasan sebesar 43,30 HRC dan nilai ketebalan sebesar 31,00 µm. Maka dapat disimpulkan bahwa semakin dekat jarak antar anoda-katoda dan semakin lama waktu proses pelapisan dapat meningkatkan nilai kekerasan dan ketebalan lapisan hardchrome.

The King Pin is one of the main components in a truck made of ST41 steel. During a survey conducted at Alfian Motor workshop, it was found that steering system damages are often caused by issues with the king pin. Additionally, there is a shortage of original king pin spare parts in the field, leading people to use non-original parts. The quality of non-original king pins is significantly low, with a hardness of 43.3 HRC, compared to the original king pins with a hardness of 64.1 HRC. The low quality of non-original king pins can be improved by applying a hard chrome plating process, which aims to investigate the effects of variations in anode-cathode distance and electroplating time on the hardness and thickness of the hard chrome coating.

In this experimental research, hardened king pin specimens were used and coated with hard chrome, with variations in the anode-cathode distance of 10, 15, and 20 cm, and plating times of 60, 75, and 90 minutes. Data collection was done by measuring the hardness and thickness values of the resulting coatings using a Leeb Hardness Tester and a Coating Thickness Gauge as research instruments. The data obtained were then analyzed to determine the influence of the independent variables on the dependent variable using the ANOVA method to assess the level of significance of each variable used.

The research results showed that the highest hardness and thickness values were obtained with a 10 cm anode-cathode distance and a 90-minute plating time, resulting in a hardness value of 67.68 HRC and a thickness value of 51.85 µm. On the other hand, the lowest hardness and thickness values were observed with a 20 cm anode-cathode distance and a 60-minute plating time, resulting in a hardness value of 43.30 HRC and a thickness value of 31.00 µm. Therefore, it can be concluded that decreasing the anode-cathode distance and increasing the plating time can enhance the hardness and thickness of the hard chrome coating.