When evaluating a grub screw factory, you must prioritize material grade and dimensional precision. Common materials include Stainless Steel (SUS304/316) for corrosion resistance and Alloy Steel (Grade 12.9) for high-tensile applications. Ensure the factory adheres to international standards such as DIN 913, DIN 914, or ISO 4026. Pay close attention to the drive type (e.g., Hex socket, Slotted) and the point style (e.g., Cup point, Flat point, Cone point), as these determine the screw's locking efficiency and application suitability.