Cam Terminology

Scalar See Vector
Seizure The melting effect over an entire surface where the friction caused by two metal members slipping against one another, such as in shaft and shaft bearing relationship, causes heating and melting onto the opposite member's surface.

Self-Excited Vibration
A vibration that induces its own driving force. The amplitude of this vibration may intensify or continue. Stopping the vibration stops the self-excited vibration due to the absence of any external driving force. Self-excited vibrations can be distinguished from what is known as forced vibrations by trying to stop the vibration. If the driving force persists, the vibration is forced.

Sequence Control
A systematic control of motions in which the detection of an event or motion triggers the next motion and so on so that all motions occur in a given sequence. Events or motions are detected with a switch or sensor usually at the end of that motion.

Skew Angle
Angle formed by rotating direction of rotating member and rolling direction of rolling member.

The output section that converts rotational motions into reciprocating motions. A well known example is the crank piston mechanism.

Slope Angle
The angle of a hill. That is, the angle formed by the slope and a reference line. For instance, in a knife edge follower for a translating cam, the slope angle of the cam surface must equal the slope of the pressure angle of the cam surface.

A scraping effect that occurs when two contacting surfaces rotating at different peripheral speeds make sudden contact or when a foreign particle intrudes. When the rolling member slips instead of rotating normally against the raceway surface, the oil film on both members dissolves and causes smearing to occur over a small area.

S-N Curve
The phenomenon where a material breaks after repeated exposure to a certain amount of stress is called material fatigue. The S-N curve (Wella curve) represents repetitive stress σ and the number of cycles to breakage N.

Solid Cam
A cam that produces a 3-dimensional motion. 3-dimensional cams occupy less volume compared to plane cams. Can be used as positive cams.

Spherical Cam
A solid cam with a expanded center.

Static-Rated Load
The maximum load allowable during idle condition. When the machine or equipment is idling or operating at a relatively slow speed, static loads in excess of a certain degree of stress or strong impact loads can induce permanent damage to thrust bearings and rolling members of the bearings causing noise and vibration to occur.

Static-Rated Output
Maximum torque that can be applied to the output shaft during dwell.

Steel. Generic term referring to all metals with a carbon ratio of content of 0.035 to 1.7%. Common steels are referred to as carbon steels and other steels containing such elements as Ni, Mn, and Cr are referred to as special steels.

The distance traveled by a given object that starts from a stopped condition to the next stopped condition.

Surface Roughness
The precision to which the cam surface was finished. Represents the irregularities on the surface in μ micron units.

Synchronized Control,
Overlap Control
When using cams, the operating time is strictly dictated by the mechanical rotating angle of the cam. The position of the follower at any given point during the output stroke is also definitive and never changes. This characteristic makes it possible to start another motion at the same time to reduce the overall cycle time. Such control is referred to as synchronized or overlapped control.

In a cam link mechanism, the technique used to determine the length or position of a link to obtain the desired input, output or trajectory.