Long Lasting Lag Screws Square Head

For each batch of Long lasting Lag Screws Square Head from supplier Xiaoguo®, from raw materials to finished products, we undergo at least six rounds of inspections. It's not a case of testing just one or two pieces, but instead, we conduct random checks on key items by batch.

Raw material inspection

The raw materials are first sampled for spectral analysis to confirm that their chemical composition conforms to the 10B21 or Q235 standards.

Post-cold heading inspection

After the cold heading machine produces square heads, the workers take out 5 pieces every half an hour to check the dimensions, height and for any cracks on the edges. They use a vernier caliper to measure the opposite sides, with the tolerance controlled within ±0.2 mm.

Random inspection after threading

During the production process of the threading machine, 10 pieces are randomly selected every 1 hour. Check whether the thread profile is complete, and whether there are burrs or folds. Measure using a thread gauge.

Post-treatment inspection

Take 3 samples from each furnace, make a cross-cut at the head, and measure the surface and core hardness using a Vickers hardness tester.

Inspection before shipment of finished products

Before packaging, 5 Long lasting Lag Screws Square Head out of 500 pieces from each batch are randomly selected for full-size testing, along with an inspection of the appearance. After packaging, the label information, quantity, and sealing condition also need to be checked.

Tips for extending the service life

The Long lasting Lag Screws Square Head are difficult to replace once inserted into the wood, so precautions should be taken during installation. The following three steps can significantly extend their lifespan.

Choose the right material

Choosing the right material is like insuring the screws for a long-term period.

Indoor dry environment: Carbon steel + electro-galvanizing

Indoor dampness or occasional water splashes: Use stainless steel 304

General outdoor use: Use hot-dip galvanized carbon steel or stainless steel 304.

Coastal outdoor: Must be made of stainless steel 316.

Correctly drill the pilot hole

The diameter of the guiding hole = 60% - 70% of the Long lasting Lag Screws Square Head diameter.

The hole depth should be ≥ the effective thread length of the screw + 10 mm.

Keep the drill hole vertical and do not tilt.

Use washers

The bottom of the square head is flat. But when it is directly pressed onto the wood, over time the wood gets compressed and the screws loosen. Add a flat washer:

The gasket can distribute the pressure over a large area, and the wood will not sink.

Outdoor applications must use hot-dip galvanized or stainless steel washers.

The inner diameter of the washer is slightly larger than the diameter of the screw.

When installing, the washer should be tightened simultaneously with the screw head. The washer should be slightly embedded into the surface of the wood.