Roughness measurement methodology for selection of tool inserts

Contribution introduces practical methodology of roughness measurement when turning by tool inserts with variable tool face. Methodology makes the most of use standardised chip cross sections from ISO 3685:93. Measuring array consists of combination of four feeds per revolution and three depth of cut while use of two cutting speeds denotes such methodology as 4–3–2 roughness measurement. Minimum replication is used when measuring roughness in order to identify its quantities where cutting starts and stops. Data resulting from minimum replications are treated as pivot half-sums and pivot ranges, quantities following from Horn’s distribution. Four ways of results’ interpretation are expressed which include individual measured values, comparison, relationship as well as multivariate form of measured data. Individual values represent results from just one point in measuring array; comparison covers half-sum results all over measuring area. Relationships among surface roughness parameters show how roughness ranges measuring area throughout. Considerable effect of chip cross section on multivariate form of surface roughness is given by Andrews’ plot. Processing and evaluation of data give well founded information to choice proper tool insert as practical contribution related to machining plans.

► Methodology of roughness measurement with minimum replication.
► Combination of roughness measurement with recommendations for tool testing.
► Pivot half-sums and pivot ranges expressing variability of roughness measurement.
► Capability of proposed methodology in decision making when process planning.