1
Montferrand Mécanique
Clermont-Ferrand (63)
Clermont-based facility active for over 35 years, specialised in CNC and conventional precision mechanics. Offers a wide range of processes including wire and sinker EDM…
Machining process
Keyway Broaching: Machining Internal Grooves and Profiles
Slotting (also called shaper machining or internal broaching) is a material-removal process that uses a single tool driven by a reciprocating, generally vertical, motion to create internal features: keyways, splines, non-circular profiles or internal gears. Carried out on a dedicated slotting machine or, more rarely nowadays, on a machining center fitted with a specific tool, it achieves internal geometries that conventional milling or turning cannot reach, particularly in blind bores or thick parts produced as single units or in small batches.
Where to find a slotting workshop
Cities are ranked by number of listed workshops. Each page details the companies and their specialities.
Choosing the right supplier
When to choose slotting over another process
Slotting proves worthwhile when you need to create a keyway, a spline or a non-circular profile inside a bore, particularly on one-off parts or small batches where investing in broaching tooling would not be cost-effective. It remains relevant for blind bores, thick-section parts or complex internal shapes that conventional milling cannot easily reach. For large runs of simple grooves, broaching or wire EDM are often more economical; slotting retains its place for special parts, prototypes, and repairs or rework of existing components.
The criteria that truly distinguish two workshops
A workshop's real capability shows in its slotting machine's specifications: tool stroke, available power, and the maximum bore diameter and depth it can handle. Typical tolerances achieved run around a few hundredths of a millimeter on groove width and position, though this varies with machine rigidity and tool wear. The materials worked matter too: structural steels, heat-treated steels, cast irons, stainless steel or bronzes each require different tools and cutting speeds. A good indicator of reliability is the presence of suitable inspection equipment, such as a profile projector or coordinate measuring machine, to verify the position and parallelism of the grooves or splines produced, along with demonstrated experience on one-off parts as well as small batches.
What to prepare to get an accurate quote
A dimensioned drawing with tolerances for the groove or internal profile, the material and its condition, whether raw or already heat-treated, allows the workshop to assess feasibility and machining time. Specify the quantity of parts, the expected surface finish inside the groove, any heat or surface treatments planned after machining, and the dimensions of the existing bore if slotting is being performed on a part that has already been partially machined. Stating your desired lead time also helps the workshop schedule its slotting machine and confirm a realistic commitment.
Materials most often worked with this process
slotting workshops
A selection of listed workshops, all cities combined.
2
ARAM
Rezé (44)
3
EURAMECA
Colmar (68)
EURAMECA is a precision machining workshop founded in 1991, equipped with CNC machining centres up to 4 axes and CNC lathes. The company works on prototypes and small se…
4
Mecagear
Ecouflant (49)
5
Mécanique de Précision Mulhousienne
Mulhouse (68)
Machining and turning company established in the ZAC du Parc des Collines in Mulhouse since 1998. Works as a subcontractor for the manufacture of one-off parts, prototyp…
6
Mécanique Générale Etupes
Etupes (25)
Precision engineering workshop located in Etupes, in the immediate Montbéliard urban area, offering a full range of processes including 5-axis milling and keyway broachi…
7
Mécarect
Nantes (44)
8
MPI Mécanique de Précision Issoirienne
Saint-Rémy-de-Chargnat (63)
9
MPM-Proceptis
Mulhouse (68)
Industrial mechanical engineering company established on rue Jean Monnet in Mulhouse, active in blueprint-based precision machining. Manufactures one-off parts and small…
10
SMK Plastimetal SAS
Mulhouse (68)
Precision machining company based in Mulhouse, serving various sectors including automotive, industry and plastics processing. Notably offers high-precision keyway broac…
Frequently asked questions
What accuracy can be achieved with slotting?
Typical tolerances generally run around a few hundredths of a millimeter on the width and position of the groove or internal profile. Actual precision depends on the rigidity of the slotting machine, tool condition and the material being machined; it's useful to specify your functional tolerances on the drawing so the workshop can confirm its ability to meet them.
What's the difference between slotting and broaching?
Broaching uses a multi-tooth tool that passes through the part in a single stroke, requiring specific tooling that is costly but cost-effective for high volumes. Slotting relies on a single tool with reciprocating motion, slower but without dedicated tooling, making it suitable for one-off parts, small batches or non-standard shapes.
What materials can be machined by slotting?
Most conventionally machinable metals are suitable: structural steels, heat-treated steels, cast irons, stainless steel, and bronze or aluminum alloys. Tool selection and cutting parameters vary according to the hardness and nature of the material, which should be specified when requesting a quote.
Is slotting suitable for large production runs?
This process is best suited to one-off parts or small to medium batches, since machining time with reciprocating motion remains longer than other methods. For large volumes with a repetitive internal geometry, broaching or wire EDM are often more cost-effective in terms of price and throughput.