Trapezoidal Nut: Bronze VS PEEK vs. PETP+SL
Although bronze is mechanically superior, the material has clear limitations: it requires constant lubrication, generates noise, and can release microscopic metal particles due to wear. For this reason, experts recommend advanced plastics in specific practical environments.
1. PEEK: The Indestructible Problem Solver for Extreme Chemistry
PEEK (Polyetheretherketone) is an absolute top-tier thermoplastic. It is used in environments where metals fail immediately due to corrosion. Think of the chemical process industry or swimming pool technology, where constant exposure to aggressive chlorine environments is the norm. PEEK is virtually chemically inert, does not absorb moisture, and retains its mechanical rigidity up to very high temperatures.
2. PETP+SL: The King of Dry Running in the Food Industry
PETP+SL (Polyethylene terephthalate with solid lubricants) is the absolute favorite for the food industry. In the food sector, bronze is often prohibited due to the risk of loose bronze particles or metal dust contaminating the food. PETP+SL solves this: the material is FDA-approved, extremely wear-resistant, and contains built-in solid lubricants. This allows the flanged nut to run “dry” without external grease or oil that could attract dirt or end up in the product. Note: running without lubrication still yields lower performance than running with lubrication.
The Hard Limit: Forces and Duty Cycle
Despite the impressive properties of PEEK and PETP+SL, the engineers at Machinefabriek Harderwijk emphasize that switching to plastic is only possible under strict conditions.
Plastic insulates heat instead of dissipating it. If the nut is loaded too heavily (too many kilograms) or runs for too long continuously (high duty cycle), the internal temperature rises rapidly. This causes the nut to soften, leading to acute and catastrophic wear.
The Rule of Thumb: Plastic excels in hygiene, chemical resistance, and noise reduction, provided that the mechanical forces (surface pressure) and the running time (duty cycle) are limited. Do heavy loads need to be moved continuously? Then bronze remains the safe choice.
Material Comparison at a Glance
| Property | Bronze (RG7) | PEEK | PETP+SL |
| Maximum Surface Pressure | Very high (10-15 N/mm²) | Medium (5-7 N/mm²) | Limited (2-4 N/mm²) |
| Duty Cycle (Running Time) | Continuous (Excellent cooling) | Periodic (Moderate cooling) | Periodic / Short cycles |
| Lubrication | Mandatory (Grease) | Dry running possible | Good dry running (Maintenance-free) |
| Chemical Resistance | Moderate (Sensitive to acids/chlorine) | Extremely high (Chlorine & acid resistant) | Good |
| Food Safety (FDA) | No (Wear/contamination risk) | Yes (Depending on specific grade) | Yes (Ideal for food sector) |
Which Flanged Nut Fits Your Project?
The choice between bronze and plastic is not a matter of “better or worse,” but of the right match for your application environment. Are you building a machine for a chlorine environment or the food industry where movements are periodic? Then PEEK or PETP+SL is the most modern and low-maintenance choice. However, does the machine need to lift heavy loads non-stop? Then continue to rely on the strength of bronze.
Are you unsure about the exact surface pressure or the maximum allowable duty cycle within your design? The team at Trapeziumdraad.nl is happy to assist you.