The term workholding vice refers to a range of tools used as accessories to temporarily hold parts that are to be machined. These accessories make it possible to clamp any type of part and material firmly. Without vices, machining would not be accurate.
What is a workholding vice used for?
It is often thought that, in part machining, the most important thing apart from the workpiece is the machine tool that performs the machining. However, these machining jobs could not be done properly if the parts were not held firmly in the chucks, heads and tables of the machines. To keep the parts fixed in the position required for the job, various devices known as vices and clamps are used.
Vices not only prevent the part from moving, which ensures excellent results, but also guarantee operator safety and, of course, greater ease when carrying out the work.
A workholding vice applies pressure to the part in order to hold it on the machine bench or bed. Vices are essential not only in machine shops but also in carpentry and electrical work. This tool works by means of a screw mechanism or another type of mechanism that holds the part by friction, applying continuous pressure.
Types of workholding vices and clamps
Industry uses various types of vices and clamps for holding parts. These can have a fixed base or a swivel base. Vices can also be classified by how they are actuated, which includes hydraulic vices. The most common are the bench vice, F-clamps, locking pliers ( grip), but other tooling is also used for clamping, such as pliers and slings.
Fixed-base workholding vice
The bench vice falls into the category of fixed-base vices. This accessory provides effective, quick and very easy-to-use clamping. It allows many machining operations, such as milling, drilling and so on.
A bench vice is usually mounted on a table or bench. It has two jaws, one fixed and one moved by a square-thread screw; this screw is turned by a handle. The part to be machined is placed between these jaws. To prevent the surface of the part from being damaged by the clamping pressure, protective covers or soft jaws made from materials such as lead are usually used. The screw that holds the part can be tightened until the desired pressure is reached, preventing the part from moving.
Hydraulic vices
This is one of the most sophisticated types of vice, as it uses a spindle mechanism to operate. Some machine tools, such as drilling machines and milling machines, include hydraulic vices as workholding systems. With hydraulic vices, closing and opening are automatic, as is the clamping pressure.
These vices are available with a fixed or swivel base. In addition, hydraulic vices, which are common on machining centres, can achieve clamping forces of between 2.5 and 5 tonnes with no effort and with a manual actuation system.
F-clamps
F-clamps are tools made up of two jaws that can be adjusted with a screw which, when turned, applies pressure to the part placed between them. F-clamps are available in different sizes and are used for machining metal parts, but also in carpentry.
The smallest clamps, with a metal C-shaped body, are known as C-clamps or G-clamps.
Locking pliers (grip)
Locking pliers, also known as grip pliers, are pliers that can be locked in a specific position to pull or bend different materials. A grip consists of a handle fitted with a bolt that sets the jaw opening so that the part to be machined can be positioned. On the other handle there is a lever used to apply pressure.
Once the part is in place, it is held completely firmly and the operator can let go of the tool to carry out the machining. When the work is finished, the pressure is released by pressing the lever on one of the handles. For a tighter hold, when the parts to be machined must turn in opposite directions, two grip pliers can be used on the same part.
Locking pliers can in turn be divided into:
- Square jaws.
- Oval jaws.
- Thin jaws.
Pliers and slings
Although they are not officially considered workholding vices, they serve the same purpose. Pliers are hand tools shaped like pincers, consisting of two arms that can both grip and cut. Slings are lifting tools that are also used for clamping. Slings make it possible to secure a load by means of a lifting or towing hook. Slings are straps of specific width and length with a loop at each end.