Maintenance of Pressing and Touch Cutting Equipment with the Pneumatic System of Subang State Polytechnic

This study aims to make a preventive maintenance plan for tofu presses and cutters with a pneumatic system with the methods carried out namely inspection, small repair, medium repair and overhaul (ISMO). The preventive maintenance time on presses and tofu cutters with this pneumatic system is carried out with this type of maintenance on a monthly and annual basis. The research stages of implementing preventive maintenance on tofu presses and cutters with a pneumatic system includes literature studies, making maintenance schedules and expert validation. Components carried out preventive maintenance on the mechanical system which includes the frame, drive system, compressor and blades. data collection using observation and documentation. data were analyzed descriptively quantitative. The results showed that the preventive maintenance of tofu presses and cutters with a pneumatic system was intended to maintain the condition of the tools as well as to extend their service life and streamline the production process.


INTRODUCTION
Tofu is one of the processed soybean products that has a fairly broad market segment.Added by [1] tofu is produced by utilizing the nature of protein, which will clot when reacted with acid (vinegar).
Clumping of protein by vinegar will take place quickly and simultaneously in all parts of the liquid soybean juice, so that most of the water that was originally mixed in the soybean juice will be trapped in it.The trapped water can be removed by applying pressure.The greater the pressure applied, the more water can be removed from the protein clump.The clumps of protein are then referred to as tofu.
The process of making tofu on a home scale is generally still done in the traditional or manual way, especially in the process of squeezing or pressing soybean juice.The process of squeezing or pressing soybean juice from tofu dregs requires a lot of energy and a long process.To help the process of squeezing soybean juice to be more effective and efficient, a tofu press will be developed simultaneously with a tofu cutting machine using a pneumatic system.
In the process of using tofu presses and cutters with this pneumatic system, of course, it requires maintenance.It aims to extend the service life and streamline the production process.Maintenance is an activity that is directed at the goal of ensuring the functional continuity of a production system so that the system can be expected to produce the desired output [2] Interruptions to the planned schedule of production and maintenance time can be eliminated or reduced [6].Tofu is a food that is rich in nutrients [7].Tofu is also a food that is consumed regularly by the Volume 6, Number Based on the results of direct observations of visits and interviews to the Subang district, there are still several things that need to be developed, one of which is making a routine maintenance schedule so that the pneumatic press and tofu cutter can always be used in a safe and optimal condition.Occupational safety and health factors are things that need to be considered in the machine maintenance process [11].

RESEARCH METHOD
This research is a type of development research.The data obtained were analysed descriptively qualitatively.The stages of the research are as follows.

Observation
This observation was carried out to find information about the tofu press and cutter with a pneumatic system.The initial method used was a direct visit to the tofu factory in the district.Subang and conducted interviews with the tofu makers, the results of the interviews conducted at the tofu factory were the lack of awareness about the maintenance of the tools used, especially the tofu presses [12], so that periodic maintenance of the tofu presses was necessary.

Component Identification
The initial step in the maintenance process after the observations made by the author is the identification of components which is done by dividing each main component to be carried out maintenance.
There are 4 main parts, namely the frame, drive system, compressor and blades [13].
The following is the classification of the components of tofu presses and cutters with a pneumatic system.Cutting knife

Maintenance Schedule Results
The results of making this maintenance schedule plan are the total time in 1 year needed in the maintenance process of Tofu Pressing and Cutting Tools with a Pneumatic System, namely inspection (1008 minutes), and small repair (150 minutes).With the time required for each of the main components, namely, the framework system (inspection 312 minutes, small repair 30 minutes), the drive system (428 minutes inspection, small repair 0 minutes).Compressor (inspection 24 minutes, small repair 120 minutes), knife (inspection 144 minutes, small repair 0 minutes).

Main Frame
The main frame of the tofu press and cutter with this pneumatic system is the main frame that will support the load from Maintenance schedule is made every 4 months.This is the result of the expert who believes that the tofu cutting tool is not always used and the machine's performance is also not too heavy so the ISMO method is carried out on the components that will be damaged.

Drive System
The drive system is one of the main parts of the tofu press and cutter with a pneumatic system.Some of the components contained in this drive system include pneumatic tubes, solenoids, air filters and pressure control valves.The following is a maintenance schedule for the drive system

Compressor
The compressor is the most important part of the press and tofu cutter with a pneumatic system because the compressor will work to provide pressure in the form of air to move the drive system.The following is the compressor maintenance schedule every 4 months.

Cutting Knife
The knife is one of the main parts of the tofu press and cutter with a pneumatic system.Some of the components contained in this knife section include a pressing plate and a cutting knife.The following is a maintenance schedule for the drive system every 4 months.

Evaluation
In the process of making plans, schedules and maintenance instructions do not always run smoothly due to the lack of references to journals and books about presses and tofu cutters with this pneumatic system, especially in their maintenance.Research [14] reinforces the above opinion that the preventive maintenance schedule is suitable for use on appropriate tools that are not used for more than 8 hours of operation [15].
The making of the schedule plan that the author proposes for validation has been revised several times by the validator related to the rationality of the maintenance time and the maintenance schedule that should be in accordance with the use of the tool, if it is appropriate then the schedule plan is valid.

CONCLUSION
The conclusions obtained from the maintenance of tofu pressing and cutting machines with a pneumatic system are the results of making this maintenance schedule plan are the total time in 1 year required in the maintenance process of the Tofu Pressing and Cutting Tool with the Pneumatic System, namely inspection (1008 minutes), and small repair (150 minutes).With the time required for each of the main components, namely, the framework system (inspection 312 minutes, small repair 30 minutes), the drive system (428 minutes inspection, small repair 0 minutes).Compressor (inspection 24

Figure 2 .Implementation
Figure 2. Conventional tofu pressing and cutting tool

Table 2 .
Frame maintenance schedule

Table 3 .
Drive system maintenance schedule

Table 4 .
Compressor maintenance schedule