Article
An Investigation into the Effect of Electro-Contact Heating
in the Machining of Low-Rigidity Thin-Walled
Micro-Machine Parts
Antoni
´
Swi´c
1
, Arkadiusz Gola
1,
* , Olga Orynycz
2
and Karol Tucki
3
Citation:
´
Swi´c, A.; Gola, A.; Orynycz,
O.; Tucki, K. An Investigation into the
Effect of Electro-Contact Heating in
the Machining of Low-Rigidity
Thin-Walled Micro-Machine Parts.
Materials 2021, 14, 4427.
https://doi.org/10.3390/ma14164427
Academic Editor: Izabela Nielsen
Received: 2 July 2021
Accepted: 5 August 2021
Published: 7 August 2021
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1
Department of Production Computerisation and Robotisation, Faculty of Mechanical Engineering,
Lublin University of Technology, ul. Nadbystrzycka 36, 20-618 Lublin, Poland; a.swic@pollub.pl
2
Department of Production Management, Bialystok University of Technology, ul. Wiejska 45A,
15-351 Bialystok, Poland; o.orynycz@pb.edu.pl
3
Department of Production Engineering, Institute of Mechanical Engineering, Warsaw University of Life
Sciences, ul. Nowoursynowska 164, 02-787 Warsaw, Poland; karol_tucki@sggw.edu.pl
* Correspondence: a.gola@pollub.pl; Tel.: +48-81-538-4585
Abstract:
Low-rigidity thin-walled parts are components of many machines and devices, including
high precision electric micro-machines used in control and tracking systems. Unfortunately, tradi-
tional machining methods used for machining such types of parts cause a significant reduction in
efficiency and in many cases do not allow obtaining the required accuracy parameters. Moreover,
they also fail to meet modern automation requirements and are uneconomical and inefficient. There-
fore, the aim of provided studies was to investigate the dependency of cutting forces on cutting
parameters and flank wear, as well as changes in cutting forces induced by changes in heating current
density and machining parameters during the turning of thin-walled parts. The tests were carried
out on a specially designed and constructed turning test stand for measuring cutting forces and
temperature at specific cutting speed, feed rate, and depth of cut values. As part of the experiments,
the effect of cutting parameters and flank wear on cutting forces, and the effect of heating current
density and turning parameters on changes in cutting forces were analyzed. Moreover, the effect of
cutting parameters (depth of cut, feed rate, and cutting speed) on temperature has been determined.
Additionally, a system for controlling electro-contact heating and investigated the relationship be-
tween changes in cutting forces and machining time in the operations of turning micro-machine
casings with and without the use of the control system was developed. The obtained results show
that the application of an electro-contact heating control system allows to machine conical parts and
semi-finished products at lower cutting forces and it leads to an increase in the deformation of the
thin-walled casings caused by runout of the workpiece.
Keywords: turning; thin-walled parts; low-rigidity parts; micro-machines; electro-contact heating
1. Introduction
Axially symmetrical parts make up about 34% of the total production in the machine
industry, 12% of which are low-rigidity shafts [
1
]. Parts of this type are used in the
aviation industry [
2
], precision mechanics [
3
], the tool industry (special tools) [
4
], and
the automotive industry [
5
]. They have irregular shapes and low stiffness in specific
cross-sections and directions [
6
]. During production, high requirements are placed on
their geometric parameters, mutual position of the surfaces, linear dimensions, and surface
quality [7–9].
Among the large variety of low-rigidity rotating parts, a special place belongs to thin-
walled parts, which are characterized by specific stiffness-to-weight ratios [
10
]. The dimen-
sions of thin-walled parts are expressed by the dimensionless coefficients
β
t
= H/D > 15
and
α
t
= d/D
≤
0.9 (where H, D, and d stand for the height and external and internal diam-
eters of cylindrical surfaces, respectively) [
11
]. Although machining of this type of parts is
Materials 2021, 14, 4427. https://doi.org/10.3390/ma14164427 https://www.mdpi.com/journal/materials
