Design and construction of a cassava grating machine


Design and construction of a cassava grating machine


Background of the Study

            Cassava (Manihot esculenta- Cratz), has been an important crop in the Philippines and in many developing countries. It is locally known as “kamoteng kahoy”, and is widely used as food, fuel, and feed. Cassava when grated is used as the main ingredient in many of our traditional food products like the cassava cake, “pitsi- pitsi”, “suman”, “bibingka”. It has become an ideal food-security crop because it is easy to grow and is drought-resistant. It has been an important food source in many developing countries

            Usually, grating is done manually by using perforated plane sheets but such process is dangerous to human hands usually the user get wounds during grating. These problems led to the design and fabrication of machines that can grate the cassava of high quality in a short period of time and reduce human labor.

            Ms. Elnor developed a cassava grater in 2006. The grating mechanism consists of a wooden grating drum. Based on the results of her study the presser is constricted that it creates much resistance in pushing and discharge hopper cannot prevent all the spills of cassava grates. The following problems were met and possible solutions were recommended.

Significance of the Study

            Further enhancement in the machine will be done to improve its efficiency and capacity thus, the study is being propose so the following consideration will be taken care of the material to be use should be locally available, the develop grater must be affordable to small- scale cassava farmers, the machine can be fabricated in local machine shop, the machine should give reasonable production performance and it is easy to operate.

Objectives of the Study

            The general objective of the study is to develop a continuous disk-type cassava grater, specifically it aimed to:

  1. To design and fabricate a continuous disk- type cassava grater.
  2. To evaluate the performance of the machine in terms of the capacity and efficiency the fineness modulus of grated cassava.

Scope and Limitations of the Study

            The study is focused only on the design, fabrication and evaluation of the machine in terms of capacity, efficiency and fineness modulus of grated cassava.

Locale and Duration of the Study

            The study was designed and fabricated at Isumbo, Sofronio Española, Palawan from January 2015 to February 2015. Pre-testing of the machine was done at Isumbo, Sofronio, Española, Palawan and final testing at Oil Mill production in WPU College of Engineering Technology from February to March 2015.

Definition of Operational Terms

  • Grater. A device with sharp-edged holes: a device with many sharp-edged holes against which something such as cheese can be rubbed to reduce it to shreds or fine particles.
  • Weld. Welding, in engineering, any process in which two or more pieces of metal are joined together by the application of heat, pressure, or a combination of both. Most of the processes may be grouped into two main categories: pressure welding, in which the weld is achieved by pressure; and heat welding, in which the weld is achieved by heat. Heat welding is the most common welding process used today.
  • Shaft. A rotating machine element which is used to transmit power from one place to another.
  • Auger. Is a device that usually includes a rotating helical screw blade to act as a screw conveyor to push the commodity towards the other end.
  • Receptacle. A space used to contain cassava tubes and grated cassava.
  • Pitch. Is defined as the axial distance between adjacent threads on a helix or screw.  In most screws, called “single start” screws, which have a single helical thread along their length, the lead and pitch are equal.
  • Angular speed. It is the time rate of turning of a body about an axis, or the rate at which a line on a revolving body is changing direction, and is expressed in angular units per unit of time.
  • Fineness Modulus (FM). Is an empirical figure obtained by adding the total percentage of the sample of an aggregate retained on each of a specified series of sieves, and dividing the sum by 100. A smaller value indicates a finer aggregate. Finer aggregates range from a value of 2.00 to 4.00, and coarse aggregates smaller than 38.1 mm range from 6.50 to 8.00.
  • Pulley system. A pulley system consists of two pulley wheels each on a shaft, connected by a belt. This transmits rotary motion and force from the input, or driver shaft, to the output, or driven shaft.
  • Perforation. Is a small hole in a thin metal sheet. There is usually more than one perforation in an organized manner, where all of the holes are called a perforation. The process of creating perforations is called perforating, which involves puncturing the workpiece with a tool.
  • Disc cutter. This is a specialized, often hand-held, power tool used for cutting hard materials. This tool is uses an abrasive grinding wheel. Each grain of abrasive on the wheel’s surface cuts a small chip from the workpiece via shear deformation.
  • V-belt.  This belt is a circular cross section belt designed to run in a pulley with a 60 degree V-groove. The V-groove transmits torque through a wedging action, thus increasing friction.
  • Pulley. A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a belt along its circumference. Pulleys are used in a variety of ways to lift loads, apply forces, and to transmit power.
  • Frame. Is the structural component of equipment that provides the strength and rigidity overall.
  • Electric motor. It is an electrical machine that converts electrical energy into mechanical energy. Electric motors are used to produce linear or rotary force (torque).
  • Shaft key. A key fitting in a shaft to secure an operating part fastened in or to the shaft.
  • Sieve or sifter. Is a device for separating wanted elements from unwanted material or for characterizing the particle size distribution of a sample, typically using a woven screen such as a mesh or net.
  • Pillow block. It is a pedestal used to provide support for a rotating shaft with the help of compatible bearings & various accessories. Housing material for a pillow block is typically made of cast iron or cast steel.
  • Mechanical efficiency. This measures the effectiveness of a machine in transforming the energy and power that is input to the device into an output force and movement. 



Development of cassava grater

            The newly developed grater machine, also known as the DA-BARPHIL Rootcrops cassava Grater, has a capacity of more than 200kg/h of cassava, which is better than the existing PhilRootcrops grater since it could only accommodate 100kg/h. It was also observed that the newly developed grater is more efficient when it comes to wasted materials. It can practically grate all the roots resulting to very negligible losses that mostly consist of fibers woody portion of the roots (Dele Cruz, 2005).