Design of a Plastic Shredder Machine

Waste is one of the problems that still unsolved especially for plastic waste. If the handling of plastic waste cannot be done well, it will have effect for the long period. The effect of plastic waste is environment problems such as: chain food disturb, contaminate ground water, air pollution, extinction anima, poisonous soil, and act. One of the handling for plastic waste is recycling. It starts with separating plastic waste by kind of plastic. The next step is crush it until it becomes small flakes. The Small flakes can be directly used for making product such as pot, filler material for mixing with road asphalt or plastic granulate for making a product by injection mold or extraction. In order to handle plastic waste into small flakes, plastic shredder can be used to realize the making of prototype of plastic shredder machine. It starts with design process. The design process of the prototype of plastic shredder machine uses the method of design Pahl and Beitz method that consists of design and describes job, design product concept, embodiment design, and design of detail. The plastic shredder machine consists of blades or cutter, transmission element with the shape of spur gear, electric motor, and body of machine. The kind of waste plastic for shred is LDPE, HDPE, PP, PSBased for the design of plastic shredder machine can produce small flake with the dimension of about 10 mm long and 1 mm wide. Keywords—Plastics, Shredder Machine, Design, Waste.


I. INTRODUCTION
Plastic waste is an inorganic waste that is unable to be composted naturally and can be harmful for the environment if it is not controlled well such as; pollute the air, water and soil, disturb the food chain, kill the animals and many more. To solve this problem, plastic shedder machine is going to be made to help the recycling process which converts plastic into other product such as vase, paving block and others.
Plastic shredder machine consists of some functional parts that work simultaneously to recycle plastic which is inverted into small parts of the plastic. Plastic shredder machine consists of cutters, shafts, gears, a coupling, a motor, and a hopper.

II. STEPS TO DESIGN PAHL AND BEITZ
The steps to design Pahl and Beitz method consist of 4 phases which are divided into some steps in each phase [1], they are: a. Designing and describing job b. Designing the concept of the product c. Designing the embodiment of the product d. Detailing design

A. Designing and Describing Job
The process of designing machine can be started with acknowledging things that are needed in operation or in using the machine and it will be developed into some function blocks that describe the way in and way out.

B. Developing the Main Solution
Here is the flow chart that shows the steps of process breaking plastic from the choosing type of the plastic that will be processed until collecting the shredder of the plastic.

C. Product Concept
The product concept is use to make sure that the concept is better then other.
Based on the alternative concept of the product, one alternative has been chosen as alternative 2 with value of 74. Then, it is expanded into full concept of the product.    Changes that happen to some elements which is shown in the diagram are expected to be able to maximize the function of the machine.

E. Document of the Product
The process of choosing the product construction that has been analyzed into some components that changes happen and gives the best result then it is documented where as done as follows. Where:

A. Force
This construction have two kind of force are tension force and shear force.    The formula shear force for blades [4] used is Furthermore the formula tension force for blades used is The shear force is 1.732 [N] per tooth and the tension force is P (Ft) = 177.675 [N]per tooth.

B. The Torque of Machine
The force at the cutter makes torque and the diameter is 100 [mm]. the formula of torque [5] used is In this case the torque of machine is 27.257 [Nm]. When the engine rotates to produce friction, heat, etc. thus, the torque that has been obtained is add to losses of 25% from the previous torque results is 34.07125 [Nm].

C. The Torque of Motor
Motor Torque is the torque needed to rotate the engine.

D. The Power of Motor
The formula the power of motor [7] used is Based on calculations, the power needed to cut plastic is 2.34 [Hp].

H. Safety Factor for Shaft
The stress allowed from ST37 is 370 [N/mm 2 ]. The safety factor for shaft is 11.489.  The two of bearing which are greater than the operating hours allowed.

CLOSING
The design for plastic shredder machine uses Pahl and Beitz method, that consist of design and describing job, design product concept, embodiment machine, and design of detail. The design that is chosen is alternative 2, where the value is 74. The Plastic waste that will be cut is LDPE, HDPE, PP and PS. The power that is needed to cut plastic is 2.34 [Hp], and all of part have safety factor above 1 so it is safe to use.