Knowledge of screw extractors from China
A screw extractor is a tool for removing broken or seized screws.
There are many types of screw extractors on the market. We will mainly explain the common types.
Type 1
This type is one of the most popular models on the market, we also export a lot to worldwide every year. We named it screw extractor fine pitch, type A.
It has two materials, one is 35CrMo, another will be 40Cr. It is black finishing on the thread and square part while the shank is grounded.
About the material
Chromium-molybdenum steel, also known as medium-temperature hydrogen-resistant steel, is an alloy of chromium (Cr), molybdenum (Mo) and iron (Fe), carbon (C).
It has good hardenability and can be deep quenched. Due to its special high quality properties, it is often used to manufacture some high temperature and pressure resistant valves and pressure vessels,
such as CrMo safety valves, CrMo gate valves, screwdriver bits, bicycles, and so on.
40Cr is the standard steel grade of China GB, 40Cr steel is one of the most widely used steel in the machinery manufacturing industry. It has good comprehensive mechanical properties after tempering treatment, good low-temperature impact toughness and low-notch sensitivity. This steel is also suitable for cyanide and high-frequency quenching treatment in addition to the tempering treatment. Cutting performance is good, when the hardness is 174 ~ 229HB, the relative cutting machinability can be 60%. The steel is suitable for the production of medium-sized plastic moulds, shaft fittings.
Finishing
black finishing or blue finishing. The liquid and the workpiece itself react to generate a coating, the film thickness is 0.5-1.5 μm, without significant impact to the size of the parts and precision. Oxidation treatment of steel parts is widely used for general protection and decoration of mechanical parts, precision instruments, cylinders, springs, weapons and daily necessities.
Blacking process flow is: decontamination and degreasing - cleaning - pickling and descaling - cleaning - blacking - cleaning - saponification - oil immersion
For screw extractors, 35CrMo is better than 40Cr on ductile, of course the costs are higher as well.
Type 2
This type is made by rolling like type 1, it is sandblasted on the thread and square part while the shank is grounded. This model sells most to American market.
Sandblasting is powered by compressed air to form a high-speed jet beam that will be sprayed (garnet sand, copper ore sand, quartz sand, emery, iron sand, Hainan sand) to the surface of the workpiece, so that the dirt and rust can be removed.
Type 3
This is the type we recommend most. We called it screw extractor coarse pitch, type C. It is made by 42CrMo, the thread part is milled and sand-blasted, the shank is grounded. The threads have higher hardness after heat-treatment which makes it seize the bolt firmly. It also has more outstanding looking.
Type 4
This model is basically off the market.
Type 5
This model has a quick-change shank, it was developed several years ago, used on the power tools.
Type 6
Like the type 5, this model is also driven by power tools, but the material maybe better, like HSS, not very sure about its performance.
Type 7
This is a screw extractor with two heads, it is created mostly for water pipe fitting, two heads with different dimensions.
What packages do these screw extractors have?
1. Regular type, it is available in different colors. 5pcs set, 6pcs set and 8pcs set
2. Blow mold box, usually for 8pcs set
some have drill bits or tap wrench in it
3. Plastic box only for this screw extractors.
4. GSR patent box for 5pcs screw extractor set, type A.
Marking: In GSR factory, we do laser marking with any customer's logo, nice printing, clear and readable.
How to use it
