What is scratching done?

Scraping is a manual operation using a scraper, a reference surface, a measuring tool, and a display agent to grind points, measure them, and scrape them, so that the workpiece reaches the size and geometric shape specified in the process. , a finishing process that requires surface roughness and adhesion.

Because the tools used are simple, relatively versatile, have small machining allowances, and achieve very high precision, they are widely used in the manufacturing of machines and tools and the repair of mechanical equipment. Usually the guide rails, carriages and sliding bearing bushes of machine tools are finished by scraping.

Extended information:

1. Rough scraping:

If the surface of the workpiece is rough, the processing marks are deep, or the surface is seriously rusted, uneven or distorted, scrape When the margin is above 0.005mm, rough scraping should be done first. The characteristics of rough scraping are that it uses a long scraper with a long stroke (between 10mm and 15mm), a wide knife mark (10mm), the scraper marks are in the same direction, and the pieces are not repeated.

After the machining knife marks are scraped off, the points can be ground and scraped according to the highlighted high points. Stop rough scraping when the grinding points on the workpiece surface are 4 to 6 points every 25mm×25mm and the surface roughness is (Ra2.5-Ra3.2).

2. Fine scraping:

Fine scraping is to scrape off the high points after rough scraping. It is characterized by the short scraping method (the knife mark is about 6-8mm wide and 10 mm long). -12mm), the grinding points disperse quickly. When scraping finely, scrape in a certain direction. After scraping once, scrape the second time in a 45-degree or 60-degree direction to create a cross pattern.

When the average grinding points are 10~14 points per 25mm×25mm, the flatness reaches 0.01mm/500m_, and the surface roughness (Ra1.6-Ra3.2) should take into account the shape and position difference, This completes the fine scraping.

Baidu Encyclopedia—Scraping