MACHINING OF METALS AND PLASTICS
CNC Threading
TECHNOLOGICAL CONSULTING | INDUSTRIAL PRODUCTION | ENGINEERING SERVICES
CNC threading means producing internal and external threads on numerically controlled machines – with taps, by thread milling and by thread turning on a lathe. Below you will find the scope of what we can do.
MDP Precision carries out CNC threading as part of the complete machining of a part: the thread is produced in the same setup as drilling, turning and milling. As a result the thread is perpendicular to the datum face and its position relative to the remaining holes stays true to the drawing – without the deviations that come from moving the part between machines.
We operate a modern machine park: the 5-axis DN Solutions DVF 5000 (Ø650 mm table, A/C tilt and rotation 140°/360°) and DMG MORI CMX 70 U allow threading in inclined faces that are not parallel to the datum. DN Solutions DNM 750 II vertical centres handle parts up to 1630 × 762 × 650 mm and 1500 kg, while the PUMA GT3100LM lathe (1123 Nm, driven tools up to 5,000 rpm) and the LYNX 2100LYA with Y and C axes produce turned threads and cross tapping – for single pieces and series production alike.
What kinds of threads do we produce in CNC threading?
INTERNAL THREADS CUT WITH TAPS: threads in through and blind holes, produced in a numerically controlled cycle with control of the effective thread depth and synchronisation of spindle speed with feed.
THREAD MILLING: the method we use in difficult-to-machine materials, in stainless steel and titanium, in thin walls and for large diameters and blind threads. It gives an accurate profile and radically reduces the risk of breaking a tool inside a finished part.
EXTERNAL AND TURNED THREADS: metric, imperial and pipe threads produced on lathes – on shafts, spindles and connectors, including larger pitches. High spindle torque (1123 Nm on the PUMA GT3100LM) also allows threads to be turned in higher-strength materials.
TOGETHER WITH DRILLING, CHAMFERING AND COUNTERBORING: the tapping hole, the chamfer and the counterbore are produced in the same cycle as the thread – see also CNC drilling. One setup means fewer operations, a shorter lead time and better repeatability across a batch.
THE CNC THREADING PROCESS
DRAWING REVIEW: we check the type, pitch and class of the thread, the effective depth, the material and the tool access to the threaded face.
METHOD AND TOOL SELECTION: we decide whether the thread will be cut with a tap, milled or turned, and match the parameters to the material.
MACHINING AND INSPECTION: we produce the thread and then check it with go and no-go thread gauges.
We work within a quality management system confirmed by an ISO certificate and every batch of parts is inspected. We check threads with thread gauges, verify the effective depth and the perpendicularity to the datum face, and document the results. Thanks to this our parts are accepted without reservations in the most demanding industries – automotive, aerospace, pharmaceutical, marine and defence.
Frequently asked questions about CNC threading
We handle prototypes and single parts as well as series production. In larger batches we optimise the cycle and the tooling, which lowers the unit cost of the part.
Yes – CNC drilling, chamfering and counterboring are carried out in the same setup as the threading. As a result the thread is perpendicular to the face and the relative position of the holes stays true to the drawing.
Yes. In materials prone to work hardening and tool seizing we use thread milling together with matched cutting parameters and cooling. This keeps the thread profile accurate and avoids damaging the part during the final operation.
We check threads with go and no-go thread gauges, verify the effective thread depth and the perpendicularity of the thread to the datum face. Inspection takes place within a quality management system confirmed by an ISO certificate, and the results are documented for the whole batch.
A tap produces the thread in a single pass and is the fastest option in free-machining materials. Thread milling is slower but safer: the tool is smaller than the thread, evacuates chips more easily and will not seize in the hole. That is why we usually choose milling for stainless steel, titanium, large diameters and high-value parts.
We match the range to the part and the material. Smaller threads are cut with taps, while large diameters are produced by thread milling – this method gives an accurate profile without needing a dedicated tool for one specific diameter. The size of the part is more of a constraint than the thread itself: on machining centres we work with parts up to 1630 × 762 × 650 mm and 1500 kg, and on lathes up to Ø530 mm and 1500 mm long.
As standard, metric threads including fine pitches, as well as imperial and pipe threads – both internal and external. Threads with an unusual profile or a large pitch are confirmed from the drawing, as they depend on the available tooling and method.
CNC threading is needed wherever parts are to be joined repeatedly and detachably. Most often we produce threads in the following groups of parts.
HOUSINGS AND ENCLOSURES
Threaded mounting holes in exact relative positions, produced in a single setup together with the through holes.
SHAFTS AND SPINDLES
External threads turned on shaft ends – for nuts, locating elements and threaded joints.
HYDRAULIC AND PNEUMATIC CONNECTORS
Pipe and metric threads in through holes and galleries, where the tightness of the whole system depends on them.
FLANGES AND CONNECTING PARTS
Threads arranged on a pitch circle in repeatable spacing, produced in series within the position tolerance.
BUSHINGS AND NUTS
Internal threads of large diameters and pitches – usually milled, to obtain an accurate profile.
FIXTURES AND WORKHOLDING
Threads for clamping and locating elements that determine the repeatability of the entire fixture.
STAINLESS STEEL AND TITANIUM PARTS
Materials prone to work hardening and tool seizing – here we mill the thread, with matched cooling.
WELDED STRUCTURES
Threads in components that we then join in our welding shop – machining and welding from one supplier.
