How are Mechanical Pencils Made?

Mechanical pencil, that is, a pencil that returns to its original position after the pressure is released. Mechanical pencils are divided into thick core and fine core movable pencils according to the diameter of the pencil lead. According to the core out method, it can be divided into falling core type, rotary type, pulsating type and automatic compensation type.

mechanical pencil

The world's first mechanical pencil was invented in Britain in 1822. In 1915, the Japanese person Tokusaki Hayakawa invented a mechanical pencil. The pencil was named "Every-Ready Sharp Pencil" for export. At first, this new writing instrument was not recognized in Japan. Until the export orders surged and was recognized abroad, domestic demand in Japan grew rapidly. Hayakawa also expanded with sales of mechanical pencils.

Mechanical pencils began to spread on Japanese campuses in the late 1970s, and were produced in large quantities by Sharp Corporation of Japan. Mechanical pencils need to be placed in fine graphite

The drop core type automatically pulls out the lead core by the gravity of the lead core. Rotary conveying lead core by rotation. The pulsation type (swing type) relies on the movement of the lead core. The structure has a one-time type, that is, the lead core is moved out once. Two-movement type, the first movement of the nib to extend the pen, the second movement of the lead core to extend. Double chuck swing type, using double chuck structure, shortens the distance between the chuck head and the tip of the pen tip, so that the last remaining lead of 8 to 15mm in the movable pencil can be used to produce a whole lead The core pushes it out for continuous writing. The automatic compensation type (automatic core removal) does not require a rotation or pulsation device, and can automatically compensate the lead core for continuous writing.

Pulsed movement structure is active

The special lead of the thin-core movable pencil has the characteristics of high flexural strength and good writing performance. It mainly uses synthetic resin as the lead core binder. Commonly used are polyvinyl alcohol, asphalt, furan resin, polyvinyl chloride, ABC resin, vinyl chloride-vinyl acetate copolymer, etc .; graphite is used as the lead colorant; Common solvents are water, ethanol, etc .; dioctyl phthalate, tricresol phosphate, etc. are often used as plasticizers to reduce the flow viscosity of the resin at high temperatures and improve the molding performance; lead stearate is often used. As a stabilizer, it can prevent the resin from aging and inhibit the oxidation process. It uses liquid paraffin and low molecular polyethylene as lubricants to improve the flowability of the resin melt.

The resin fine lead core is manufactured under high temperature baking and carbonization under the protection of an inert gas (such as argon) or sealed conditions to form a graphitized structure, which has high mechanical strength and good writing performance.