Stainless steel precision hardware M4 semi-threaded Draft Beer mechanical parts

Application and Characteristics of Food-Grade Stainless Steel Pins in Beer Machine Components

1. Core Application Scenarios

2. Key Materials and Performance Characteristics

2.1 Main Material Selection

• 304 Stainless Steel (SUS304)

   

  Contains 18–20% Cr and 8–10.5% Ni. Cost-effective and resistant to weak acids, alkalis and standard beer media. Suitable for general brewing conditions (alcohol ≤5%, no high-chlorine cleaning).

   

  Compliance: Must meet GB 4806.9-2023 National Food Safety Standard – Metal Materials and Articles in Contact with Foodstuffs. Heavy metal migration limits: Pb ≤0.01 mg/dm², Cd ≤0.005 mg/dm².
   
• 316 Stainless Steel (SUS316)

   

  Adds 2–3% molybdenum for significantly improved chloride ion corrosion resistance. Ideal for harsh conditions (high-salt/high-acid beer, fruit beers, frequent CIP with chlorine-based cleaners).

   

  Application: Industrial breweries, heavy-use commercial machines, corrosive brewing environments.
   

2.2 Key Performance Features

(1) Hygiene and Safety (Critical Requirement)

• Smooth, easy-to-clean surface: Non-porous, no dead zones, prevents yeast, residue and bacterial growth.
• No harmful substance migration: Alloy element migration meets food standards, no impact on beer flavor.
• Compatible with food-grade lubricants (e.g., H1) to avoid contamination.

(2) Media and Environmental Corrosion Resistance

• Resistant to beer ingredients: weak organic acids, CO₂, alcohols.
• Withstands cleaning chemicals: caustic soda, nitric/phosphoric acid, chlorine sanitizers, and thermal cycling (0°C–90°C).
• Stable in high-humidity cleaning environments, no rust or contamination.

(3) Mechanical and Processing Properties

• Strength and toughness: Tensile strength ≥520 MPa, yield strength ≥205 MPa, withstands radial load, impact and fatigue.
• Good machinability: Easily turned, cold-headed, polished; made into grooved, drilled or cylindrical pins.
• Excellent weldability: 304L/316L reduce intergranular corrosion risk after welding.

3. Surface Treatment and Processing Requirements

1. Electropolishing (Preferred)
    
   Surface roughness Ra ≤0.4 μm (even Ra ≤0.05 μm), mirror-like finish reduces adhesion. Strengthens passive film for better pitting resistance.
2. Chemical Passivation
    
   Uses citric/nitric acid to remove free iron and form a protective chromium oxide layer, with thorough post-passivation rinsing.
3. No Hazardous Coatings
    
   No toxic coatings (Cr⁶⁺, lead, etc.). Use natural finish or food-grade transparent film only.

4. Selection and Application Guidelines

1. Condition-Based Selection
   • Household / light commercial: 304 for balanced cost and performance.
   • Industrial / frequent CIP / high-chlorine: 316 for superior corrosion resistance.
    
2. Structure and Precision
   • Preferred: Type B pins with split pin holes (GB/T 882) for anti-loosening under vibration.
   • Controlled fit and clearance for smooth motion without excessive wear.
    
3. Maintenance and Compliance
   • Regular inspection for scratches, pits or wear; replace worn pins.
   • Require GB 4806.9-2023 test reports and certifications (FDA, NSF).
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We have introduced advanced equipment and technology from Japan and Germany (CNC 5-axis and 6-axis machines) to better serve our customers' needs.

Our maximum processing outer diameter is 60, and the minimum control tolerance is 0.001. We have Japanese CNC Tsugami, CNC Citizen, multi-station cold extrusion forming machines, 500T press machines, casting equipment, and various process equipment, which can effectively provide customers with the best technical solutions.

Our company has a total of 300 employees, including 20 technicians, 10 engineers, and 15 quality control personnel. We have over 300 pieces of equipment.

Our company implements 8S management and has passed ISO9001 and TS16949 automotive certifications.

Our customers include Siemens, bo-sch, Foxconn, Panasonic Motors, Husqvarna, Shimano, NVIDIA, DJI Drones, Siegenia, and Cater-pillar.