What is Taper Turning? Methods and Applications

You might have noticed parts like shafts, dowels, and couplings with consistently varying diameters from one end to another. Well, they are made in CNC Lathes or turning centers using a machining process called taper turning.

Taper turning involves material removal with a stationary cutting tool. A highly controlled material removal process allows for a uniform decrease or increase in the diameter of the rotating workpiece. Additionally, it is about setting the tool angle right during the process.

Let’s discuss what is taper turning, types of taper, and methods of cutting a taper.

What is the Taper Turning Process?

Taper turning process

Tapering is the process of turning cylindrical works by gradually changing the diameter along the length, which makes the shape like the frustum of the cone. Meanwhile, single-point cutting tools are used for this.

In machining, Taper turning is defined by variables like large diameter, small diameter, tapered angle, tapering rate, work length, and taper length. Among these, tapered angle and tapering rate are the more critical. The tapering rate is expressed in taper/foot, taper/inches, and taper/degrees.

How to Cut a Taper in CNC Lathes?

There are four different methods to cut a taper in CNC lathes or turning centers. Each has a different mechanism for reducing the diameter.

Let’s discuss these taper turning methods in brief;

1. Form Tool Method

This method for cutting a taper involves adjusting the tool carriage at a half-tapered angle. The angled edges remove the material changing the diameter gradually. This method is suitable for the short and sharp tapered.

2. Combined Feeds Method

As the name suggested, it involves cross-feeding of the workpiece in both cross and liner directions. This mix of feeds controls the material removal and changes the outer diameter accordingly. However, the accuracy is more dependent on the operator's skills.

3. Tailstock Offset Method

This method involves shifting the alignment of the head and tailstock, so the workpiece center axis is offset to form the taper shape. The offset (mm) is calculated based on tapered length and size. Moreover, the tailstock offset method is suitable for taper long works from extremely high to low diameters.

4. Compound Rest Method

This is a more precise and accurate way to cut a taper that is suitable for short and steep tapered items. An external attachment called a compound rest is installed at a determined angle (called rest angle) ensuring perfect alignment with the work’s axis.

CNC Precision Turning Methods for Tapering the Workpieces

Especially in CNC turning centers, the tapered designs are processed by either deflecting the angle of edges or changing the workpiece axes. The G-codes in CNC precision turning guide the tool movement according to desired tapered angles.

The following are the typical steps of precision turning to cut the tapers with tight tolerances,

CNC Programming: Define the tapering variables (angle, dimensions, etc) and write the program. You can also directly convert your design to G-codes using CAM software.
Machine and Tool Setup: Attach the cutter and align it with the work to achieve the desired tapered angle. Then, set machining parameters like feed, speed, depth, etc.
Taper Turning Operation: Start the machine and let the CNC turner guide the movement. If any deviation occurs, adjust them.

What Can Be Made with CNC Taper Turning?

The tapering turning process is used in various industries to achieve tight fittings, assembly clearances, pins, and tool profiles, and also create custom parts for specific functions.

This machining process has a role in the manufacturing of parts for automotive, medical, aerospace, construction, electrical, electronics, and home appliances.

Industry

Applications

Automotive

Tapered shafts, crankshaft ends, piston pins, and wheel hubs.

Aerospace

Turbine shafts, fuselage fasteners, wing spars, etc.

Medical

Surgical tool handles, implants, and orthopedic screws.

Oil & Gas

Drill collars, pipeline joints, casing pipes, couplings, and flange connections

Tooling

Morse taper spindles, collet holders, machine arbors, etc.

Construction

Bridge pins, truss connectors, anchoring rods, and rebar couplers.

Different Types of Taper in Machining

Various types of tapers are in practice within the manufacturing sector, defined by their purpose and functions. For example, Morse taper is popular for locking purposes, pipe thread tapers are for connecting the pipes, and tool holder tapers are for machine collets.

Morse Taper MT1, MT2, etc.
Tool Holder or Shank Taper
Conical Tapers
Piper Thread Tapers
R8 Milling Taper
V-Flange Taper

Conclusion

Taper turning has various applications for custom machining parts to assembly items. Different methods can be applied to create tapered shapes based on the design specifications, compound rest, form tool, tool post-shift, etc. The precision of taper turning depends on the right machining parameters and skills of operators. Meanwhile, CNC precision turning archives tighter tolerances through automation of machining operation.