Fastener Surface Treatment Process Comparison: Hot Dip Electroplating, Die Casting And Electroplating

In the manufacture and application of fasteners, surface treatment technology is a key link to improve product corrosion resistance, mechanical properties and aesthetics. This paper will compare and analyze three common processes - hot dip electroplating, die casting and electroplating, to help users choose the best solution according to actual needs.

 

1. Hot-Dip Galvanizing

Principle and process: The fastener is immersed in molten zinc liquid, and the zinc-iron alloy coating is formed through high temperature reaction.

Advantages:

Super corrosion resistance: thick coating (50-150μm), suitable for outdoor extreme environments (such as Bridges, transmission towers).

 

Low cost: Low price of raw zinc, suitable for mass production.

 

Long-term protection: up to 20-30 years without maintenance.

 

Cons:

High temperature may cause substrate deformation, not suitable for precision parts.

 

Uneven coating, rough appearance, need to beautify after treatment.

 

Application scenario: building steel structure, traffic guardrail, heavy bolts, etc.

 

2. Electroplating

Principle and process: Metal coating (such as zinc, nickel, chromium) is deposited on the surface of fasteners by electrolytic reaction.

Advantages:

High precision: uniform coating (5-25μm), suitable for precision parts (such as electronic screws).

 

Diversified options: can be galvanized (corrosion resistance), nickel (wear resistance), chromium (decoration) and so on.

 

High aesthetics: smooth surface, customizable colors.

 

Cons:

Thin coating, long-term outdoor use easy corrosion.

 

The waste water contains heavy metals and the cost of environmental protection is high.

 

Application scenario: auto parts, home appliances, high-end decorative parts.

 

Third, the relationship between Die Casting and surface treatment

Note: Die casting itself is a manufacturing process, often used to produce zinc/aluminum alloy fasteners. The surface of the die cast usually requires additional treatment (such as electroplating or spraying), but the characteristics of the die casting process affect the subsequent treatment:

Advantages:

High surface finish of die castings reduces the need for post-processing.

 

Can form complex structure, suitable for special-shaped fasteners.

 

Limitations:

Limited materials (such as aluminum die casting plating requires special pretreatment).

 

Internal pores may reduce coating adhesion.

 

Application scenario: Lightweight fasteners (automotive, 3C products), need to be used in combination with electroplating or anodizing.

 

Process comparison table

Parameters	Hot dip electroplating	Electroplated	Die casting+ surface treatment
Coating thickness	50-150μm	5-25μm	Depending on subsequent treatment
Excellent corrosion	Resistance (outdoor)	Good (indoor)	Medium
Cost	Low	Medium high	high (mold + post-processing)
Environmental protection	medium (zinc fume treatment)	Low (containing heavy metals)	medium (die casting exhaust gas)
Appearance	rough	smooth beautiful	depends on post-treatment

 

Selection suggestions:

Extreme environment: hot dip electroplating (such as wind power bolts).

 

Precision and beauty: Select plating (such as electronic equipment screws).

 

Lightweight requirements: die casting + plating/anodizing (such as automotive fasteners).