Page 87 - UniorTools-Eng

A special procedure for the manufacture

of pliers

1. Cutting: Cutting material is the "rst operation in the technological procedure of wrench manufacturing.
Optimum design of a cut provides optimal use of material.
2. Forging: Forging technology at Unior ensures excellent strength characteristics of wrenches. Notably, it

maintains appropriate "ber orientation in a forged part, leaving it uninterrupted and the same as in a rolled blank.
That characteristic of forged parts is vital for achieving the characteristics of products exposed to heavy and
dynamic loads.

3. Trimming: Excess material is removed from forged parts using a special-purpose tool that trims products
along the dividing shape. Some products are also trimmed when hot, thus preventing major mechanical surface
deformation on the cut part and providing a quality basis for undisturbed machining.

4. Joint processing: Using a special-purpose CNC machine, a bore hole is drilled that will serve as the pivot point
for pliers. At the same time, the joint is milled and sliding surfaces are made, ensuring precise and undisturbed
movement of pliers during use.

5. Broaching

6. Shaping the head part of pliers: Using a special-purpose trimming tool with linear movement, complex
surfaces of pliers are shaped. That operation includes the shaping of external radii of the joint and teeth on the jaw
used to grip various shapes.

7. Milling the cutting edges: A special-purpose CNC machine is used for making cutting edges, thus giving
pliers the relevant functionality. Important elements are the angle of a cutting edge and the thickness of the edge
top. Optimum and accurate machining of cutting edges gives pliers the properties required to cut wire.

8. Riveting: Pliers are assembled and riveted together with a rivet. At that stage, it is important to ensure that the
joint is "rm enough, while still allowing the jaws to move freely, but with no slack.

9. Wet grinding

10. Machining the head part of pliers: At that stage, the surface of pliers is evened to remove any di!erences
in height that might appear as a result of thickness tolerance margins when making a forged part or during further
machining, including riveting.
11. Shaping: Using a tape grinding machine, the remaining untreated surfaces are ground to create better quality
surfaces than can be achieved in the forging process. The pliers now have their "nal shape, but the roughness of

individual surfaces still needs to be adjusted.
12. Quenching and tempering: The heat treatment of pliers is carried out by annealing pliers in oil and then
tempering them. Such type of heat treatment ensures an appropriate microstructure of the material and excellent

strength properties of the "nal product. Quality heat treatment maximises the mechanical properties of the
material and gives pliers a long service life.
13. Sanding: At this stage, the product surfaces are struck with abrasive materials to even the roughness of
surfaces and remove the oxides that appear during heat treatment. The sanded surfaces are evenly rough and
precise, giving products a better appearance. Some surfaces are later even more precisely treated, giving them a
contrasting look.

14. Induction hardening: The cutting edges of pliers must be covered with a thin layer of very rigid surface that
is able to withstand damage caused by cutting solid wires.

15. Fine grinding: Using tape grinding machines, speci"c surfaces on the head of pliers are ground to make
them smooth, also giving them a visual e!ect or professional appearance.

16. Chrome plating and polishing: Pliers are galvanised with a thin layer of nickel and chromium to prevent
oxidation. That gives the products an aesthetic appearance with a glossy silver surface. Chrome-plated surfaces
also make the pliers more resistant to external in&uence.

17. Laser inscription: Using the modern process of laser inscription, pliers are inscribed with markings used for
product identi"cation.

18. Insulation mounting: Pliers are completed with plastic handles providing a good, "rm and ergonomic grip.

19. Oiling and control: The sliding surfaces of a joint are properly oiled to ensure unimpeded movement of pliers. In
that operation, pliers are properly checked for quality and visual characteristics to ensure that Unior pliers always meet
the requirements of the most demanding of users.

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