COMPETENCES
Working Technologies
SPIRAL INGRANAGGI has a full set of technologies that cover the necessary working phases, including the broaching, tooth gear, gear, hard turning, lapping, bevel gears pairing, cylindric and bevel gears tooth grinding, EDM, skiving and ancillary operations.

BROACHING
Broaching is one of the most important methodologies to make teeth by forming. SPIRAL has 16tons broaching machines to make grooved profiles and keyways.
- Broaching Machines (V.R.V.)

TEETHING
Teething is a processing that, by using machine tools called toothing machines, has the task to make sprockets with external, internal toothing and spline profiles. Spiral has got gear hobbing and gear cutting machines
- Creator teething machines: EMAG – KOEPFER, PFAUTER
- Gear cutting machines: LORENZ
- Hobbing Skiving machines: EMAG – KOEPFER

GRINDING
Grinding process is one of the most delicate phases withing the production process, since it is an high precision working process. SPIRAL has got machines for the bevel gears grinding and can count on historical partners for the cylindric gears grinding.
- Cylindric gear grinding (MORARA)
Achievable tolerance:
- Planarity: below 5 µm
- Parallelism: below 5 µm

HARD TURNING
Hard turning is an alternative working process to the grinding . It is a holes and plane finishing operation on cemented gears to bring the heat treated component surface to an optimal status, both in geometrical and roughness terms. The process is made by dedicated and specific inserts.
SPIRAL INGRANAGGI is equipped with single-spindle turning machines, with manual and automatic loading.
- Turning machine (EMAG, TSUGAMI)

SKIVING
It is possible to use the skiving finishing on cylindric gears submitted to heat treatment of hardening or carburizing, where an high quality teething is requested.
This finishing is made by a hard metal hobbing tool and can provide a finishing quality comparable with teething grinding, but at much lower costs.
- Skiving machines: (EMAG-KOEPFER)

BEVEL GEARS GRINDING
To finish bevel gears, SPIRAL INGRANAGGI can use a grinding processing. With this operation, small strains deriving from the heat treatment can be corrected, by positioning the contact in the requested position, reducing the functioning noise. This operation is a sort of coupling between the pinion and the crown that gear up together, they are tested on a Gleason tester and identified with the same coupling number to be rigorously mounted together.
SPIRAL INGRANAGGI is equipped with “lappers” for the grinding and tester for the subsequent check.
Hardened bevel gears with an hardness of HRC 59–62 are subject to deformations due to the heat treatment.
By the grinding process it is possible to have and to maintain topographies within the range of few microns, as well as for the teeth thickness, to optimize the contact and the roughness degree.
- Bevel gear grinding machines: (Gleason)

BEVEL GEARS GRINDING
Cemented Bevel gears with an hardness of HRC 59–62 are subject to deformations due to the heat treatment.
By the grinding process it is possible to have and to maintain topographies within the range of few microns, as well as for the teeth thickness, to optimize the contact and the roughness degree.
- Cylindric grinding (MORARA)
Auxiliary operations
External finishing and defect correction work to ensure the highest quality of the final product
TUMBLING
The tumbling phase is a process used to eliminate surface defects due to previous processes. Tumbling scope is to obtain a defectless and shining surface. This kind of operation allows to simultaneusly work on many pieces ensuring an even and smooth finish over the entire surface.
Spiral can count on several tumbling machines (RÖSLER), with different size and capacity.
WASHING
The industrial washing is carried out to remove impurities (metallic and non-metallic particles and organic pollutants) deposited on the surface of the component from previous processing and/or treatment. Use of water/solvent metal washers.
ASSEMBLING
Spiral performs assemblies of high-precision mechanical components especially planetary gearbox carriers.
MICROPALLING
Also called “shoot peening,” it is a surface treatment performed on mechanical components in order to improve their performance during stresses. Jets of glass or ceramic shot are directed through the shot peening machine to the surface of the component.
The result is increased fatigue resistance and hardness of the treated component.
EDM
Process used post heat treatment to make special machining not obtainable by the milling process.
HEAT TREATMENTS
Spiral relies on trusted partners to perform heat and surface treatments, including:
- Carburizing
- Carbo-in
- Nitriding
- Induction hardening
- Burnishing
- Manganese phosphating
- Galvanizing