Machining time and number of machine for the production planning of wheel nut releaser with the demand of 100 units/day

Received Dec 17, 2018 Revised Feb 6, 2019 Accepted Feb 17, 2019 The impact of competition in the industry has driven people to improve the effectiveness of production process. One of the main factors supporting that effectiveness is the good planning of both the need and the number of machines. The aim of this study is to estimate the machining times to determine the number of machines to manufacture 100/day of the nut releaser tool for car wheel. The result shows that the need of the number of machines to manufacture each component of the nut releaser tool for car wheel are 7 units of power hacksaw, 27 units of lathe machine, 8 units of drilling machine, 12 units of milling machine, 2 units of EDM machine and 25 units of bench work.


INTRODUCTION
To effect the effectiveness of the production process of the nut releaser tool for car wheel, there is required a planning of needs of machines based on the estimation or calculation of precise machining time. In the era of industrialization, the factory is no longer merely a simple manufacturing consolidation but is a set of integrated technology systems with the optimal arrangement and planning. The advanced technology and good product design will be meaningless due to the imprecise planning. Mistakes made in the planning of the need of machines will lead to fatal losses, as the production activities of an industry will run for a long time [1].
Machining Time, symbolized by (Tm), is the range of time taken by a machine to work on one unit of product [2]. The accurate estimation of machining time is essential for estimating the production costs, as well as assisting production process planning [3]. To produce the nut releaser tool for car wheel, the machines and facilities used are power hacksaw, lathes machine, milling machine, drilling machine, EDM machine and bench work, with the differences of machining time for each machine. The differences of machining time for each component of the nut releaser tool for car wheel, as shown in Figure 1, are influenced by the design and dimensions of each component.

Technical drawing of each component
The main data required in this study is the technical drawing for each component. Figure 1 is the technical drawing for each component of the nut releaser tool for car wheel.

The calculation of machining time
The calculation of machining time on power hacksaw is determined by the thickness of material to be sawed, t (mm); number of strokes, V (strokes/min) and depth of feeding, f (mm/strokes) with the expression as (1) [4]: Other parameters for determining the machining time on power hacksaw may refer to Westermann Tables for The Metal Trade [5].
There are two main types of work on the lathe machine, ie facing and longitudinal cutting, with the expression of each as (2)  where df (mm) is the length of surface to be removed; i (mm/rev) is the intensity of feeding; S is feed rate; Sf (mm/rev) is feed rate for facing process; N (rev/min) is the rotation of engine spindle; and l (mm) is the length of the surface to be removed plus the tolerance of 1.
Other parameters for determining the machining time on the lathe machine can refer to Westermann Tables for The Metal Trade [5].
On the milling machine, the calculation of machining time is influenced by both the total path length, L (mm); and feed rate, s (mm/rev), with the expression as (4) [3]: Other parameters for determining machining time on the milling machine may refer to Westermann Tables for The Metal Trade [5].
The calculation of machining time on the drilling machine is determined by the length of the drilling tool, L (mm); the depth of the material to be drilled, l (mm); diameter of the drilling tool, d (mm); feed rate, S (mm/rev); and cutting speed, v (m/min) with the following expression [5]: where, L = l + 0,3d Other parameters for determining machining time on the drilling machines may refer to Westermann Tables for The Metal Trade [5].

Standard time and Output Standard
Based on the data of the machining time calculation, it can be determined the Standard time (ST) and Output Standard (OS). ST is a standard of time estimation taken by a machine to produce one component after added by the setting time, auxiliary time and allowance time. Formulated in an expression as (7) [7]: ST = Tm + Setting time + Allowance time + Auxiliary time (7) OS is the quantity of the product that can be produced by a machine within a day. On the nut releaser tool for car wheel factory, there are assumed three shifts of work within a day, 8 hours for a shift. The OS value itself can be determined if the value of ST has been determined by converting the unit as (8) [7]:

RESULTS AND DISCUSSION
Based on the calculation of machining time of each component, there is obtained the data of calculation as presented in Table 1. The next step is the calculation of material requirements for each component for each stage of the process, with the defects assumed as 0.5% on power hacksaw, 1% on lathe machine, 1% on drilling machine and 0.5% on bench work. The calculations are solved by (9) Table 2. In Table 3, there is the total calculation of the need for the machine to produce all components of the nut releaser tool for car wheel with the demand of 100 units/day. From the Table 2 and 3, it appears that lathe machine is the most needed type of machine in the manufacturing process of the nut releaser tool for car wheel with the demand of 100 units/day, with a total of 27 units. The amount is followed by bench work facilities (15 units) and milling machines (12 units) as the most needed machines. EDM which is a type of very expensive price-machine has the smallest need of 2 units. These results indicate that the planned estimates have a good efficiency as well as the high economic side.

CONCLUSION
In this study, it can be concluded that the number of machines and facilities needed to produce 100 units of the nut releaser tool for car wheel is 7 units of power hacksaw, 7 units of lathe machine, 8 units of drilling machines, 12 units of milling machines, 2 units of EDM machines and 25 units of bench work facilities. However, further study needs to make a more effective planning according to the modernization of machine and facilities.