Introduction All parts have surfaces. Depending on their function, different types of parts require different types of surfaces. Some parts require a smooth surface finish, like the ball bearing and some require a rougher surface. There are various instruments to measure surface roughness. The most common type is portable surface roughness tester or surface profilometer. Most of these devices use diamond stylus connected to a probe. The stylus is a cone-shaped, spherical tip that contacts the surface being measured. It moves at a constant speed perpendicular to the lay pattern and traces the irregularities irregularities across the work piece surface. The distance the stylus travels is the cut-off. This movement is converted into an electronic signal and read by the instrument. It is a handy-type device that eases surface roughness measurement measurement tasks, i.e. selection of parameters to measure, adjusting the position of the stylus, reading of information (surface roughness parameters, printing of information (measurement results), management and calculation of information in digital systems and reading memory cards.
Objective This practical task will be used to demonstrate the student’s ability to measure surface roughness obtained from various manufacturing processes. It will used to interpret the student’s knowledge and understanding of the theories and techniques discussed within the topics into their practical application.
Main Resources 1. Roughness Precision reference Specimen (Mitutoyo :SJ-30)
2. Surface Replica 1 ( cylinder surface ) 3. Surface Replica 2 (milling surface ) 4. Surface Replica 3 (grinding surface )
Picture 1 : main resource
Theory Calibration (Gain Adjustment)
After setting the roughness specimen in place, touch the [CAL] button in the Home Screen. Default setting for calibration Cutoff length :2.5mm Number of sampling length : 5 Measured profile :R-profile Filter : Gauss •
Touch the [Specimen roughness] button if the displayed value need to be modified to the actual roughness of the specimen. The specimen Roughness Input screen is displayed. Change the value on the screen. After changing the specimen roughness value, press the [ START/STOP] key.
Calibration measurement is performed. A bar appears on the on the screen indicating the process of calibration. After the measurement is complete, the measurement data is displayed.
Touch the [ENTER] button. The calibration factor is update, and the calibration is complete Measurement
After setting up the SJ-301 on the workpeice, press the [START/STOP] key. Default setting for measurement Standard :JIS200i Cutoff length : 0.8 mm Number of sampling length : 5 Measured profile : R-profile Filter :GAUSS •
Measurement starts.
After the measurement is complete, data processing is performed. A bar appears on the screen indicating the process of data processing.
After the data processing is complete, the measurement data are displayed. Resources and Facilities
Result (cylinder surface)
Ra : 2.02 µm Rz : 10.12 µm
Rt : 18.12 µm Rp : 5.87 µm (milling surface)
Ra : 0.66 µm Rz : 5.22 µm
Rt : 8.48 µm Rp : 1.83 µm (Grinding Surface)
Ra : 0.35 µm Rz : 2.37 µm Rt : 2.93 µm
Rp : 0.95 µm Conclusion We able to measure surface roughness obtained from various manufacturing process. These interpret our knowledge and understanding of theories and techniques discussed in this topic into practical application.
Discussion We can see the result of number (Ra,Rz,Rt,Rp), where the smaller of number of Ra,Rz,Rt,Rp the smooth of surface.
suggestion / comment
The sensor of portable surface roughness tester difficult to stand at worktable. So, we suggest the equipment must be improve at the supporter/ stand of sensor.
The advantage of this machine is easy to carry to any place. References Surftest SJ-301 Quick-reference Manual Bulletin 1967 ( 2009 Mitutoyo America Corporation, Aurora) http://www.mitutoyo.com • • •
