AUTOMATION IN DEBURRING/ FETTLING OF CASTINGS

Introduction

          In Indian automotive industry, die casting or forging plays a major part, if we talk about overall usage of component or parts in automotive industry. For example, the heart of any automobile the Engine is completely made up of either Aluminum or cast iron, the components inside an engine are also either of aluminum or cast iron. Yet I feel both these industries Die-Casting as well as Forging are highly neglected by OEM’s and so the owners of these companies. Whereas, the man force working in these industries works under typical atmosphere of heat and moisture sweating all day long. Yet 90% of such industries in India are still operated manually. If we talk about Europe or even China, it is the other way round.

So, what it is that acting as a hindrance in adaptation of these automation in Indian Industry?

1.      Lack of skills. (Skill set was never a constraint for Indians)

2.      Availability of manpower in abundance. (Then why China is leading automation now?)

3.      ROI is very delayed. (Have you measured on parameters of Quality, consistency, reduction in rejection cost, better outputs?)

One of the major concerned area where a huge chunk of manpower is invested in these industries are pre finishing processes like:

1.      Deburring/ Deflashing

2.      Buffing/ Polishing

It is not only manpower but maintaining 5S or cleanliness of the entire shop floor is difficult due to these manual processes. Another area of concern for me nowadays in the period of COVID-19 is safety of employees and following social distancing.

Burrs and Deburring

         A burr is defined as an undesirable effect generated at the edge of a work piece after the machining process. In a broader sense, burrs can also be generated during casting, forging, sintering, welding etc. Sometimes a burr is different from a flash, but both are common in affecting the processes that follow. For example, a burr can be a major hindrance in assembly work and the sharp edge of a burr can cut a worker’s hand. Also, in general, burrs give the appearance of a poorly finished product.

         Deburring can occupy as much as 10% of total man hours, yet in many cases, it is generally regarded as a minor problem or just a bothersome phenomenon. As the demand for quality becomes more rigorous, and the role of process automation becomes more important, it is necessary to devise a substantial and systematic prescription against burrs and flashes. The best solution is that a burr should not be generated in first place. Finally, the burrs that are generated must be removed, in which case, a deburring methodology, automation, process planning must be thoroughly investigated.

Robotic Deburring

         Robot automation systems for the deburring process have been developed primarily for the automotive industry, kitchen products and the manufacture of plastics. The motivation is due to the:

?    Reduction in the available work force.

?    Industrial environmental problems such as dust.

?    Demand for cycle time reduction.

?    Social distancing (New scope been added)

         The Robot automation system of deburring is composed of a robot, deburring tool and peripheral equipment. The most important peripheral equipment is the fixture device of the work piece. This device may be a simple clamping table, an indexing table, or a sophisticated manipulator depending on the geometry of the work piece and conditions such as cycle time.

         The selection of the correct deburring tool is extremely critical for the success of the process and, therefore, is an essential part of the deburring process. Also, more than thirty-five methods have been reported for the deburring process. The most important criterion in choosing one method over another is the minimization of total manufacturing cost. Primary items that must be considered are the production volume, the cycle time, the material properties, tolerances, geometry, and dimensions. Secondary items are the investigation of the process that generates a burr and the purpose of burr removal. The best solution can only be obtained when all these conditions are thoroughly investigated.

         In the robot automaton, robots are performing operations such as deburring, polishing, grinding and light duty cutting. The robots for these processes require a higher stiffness and rigidity, especially in the wrist area, compared to robots for applications such as arc welding. Industrial robots have a limited rigidity especially at the wrist and, therefore are not suited to process applications. Sturdier robots are typically designed with speed reducers, made of gear assemblies that can be used for machining processes. In some cases, dedicated robots are developed for this specific purpose. These robots are generally designed to withstand the inevitable dust and chips.

The major application areas of industrial robots include:

?    Deburring of automotive engine blocks, crankshafts, and camshafts.

?    Deburring and finishing of die casting products.

?    Polishing and buffing of die casting, forging or kitchen products

?    Cutting and drilling of plastics.

Deburring Tool

        The most common tools for robot deburring automation are flexible tools, solid burrs (rotating files), oscillating files and internal deburring tools, belts, and brushes. The most widely used tools in robot deburring automation are solid deburring tools, these are basically rotary files made from various materials that have many different shapes. The selection of correct tools is based on the geometry, material property, location, and the volume of the burrs to be removed.

Tool Holders

         Solid burrs do not absorb the reaction during the burr removing operation. Also, the volume and the hardness of the burrs are not uniform. Therefore, the results may not be uniform and the robot and spindle are exposed to unexpected shock. In such cases, the robot may stop running and provide an error message. To protect the system from this situation, tool holders should be provided with certain compliance functions. A simple solution is to use basic compliance function provided by the tool holder itself while a sophisticated system may use a specially designed integrated spindle and tool holder system.

The selection of robot deburring tools is based on the following criteria:

(i)                 The selection of tool profile based on geometric accessibility to burrs.

(ii)               A decision of the correct tool compliance based on burr size and location.

(iii)              A study of tool cutting data considering cutting force and speed, tool RPM, and material property.

(iv)              A selection of spindle type and specification based on the cycle time and the manufacturing cost

5 Main Advantages of Automated Deburring

1.      Maximized efficiency Automated deburring machines can save large amounts of time and energy compared to hand deburring. Overall Cycle Time reduction Consistency in Quality and better repeatability.

2.      Safety Automated deburring also helps contribute to employee safety. Operators do not have to get close to the grinding media because it is located inside of the machine. In addition, many automated deburring machines have a safety switch that shuts the machine down with an emergency stop whenever an operator puts their fingers inside.

3.      Manpower Reduction drastic reduction in unskilled manpower in every shift and factor for cost reduction and other labour issues.

4.      Consistency No matter how skilled a metalworking team is, it’s impossible for all employees to attain flawless consistency without the use of automation. Each person grinds metal a little bit differently, resulting in different finishes from each worker. Moreover, as people get fatigued later in the shift, the amount of pressure and force they exert when grinding can change, leading to different finishes as the day progresses.

5.      Better Environment and 5S No matter how many time in a day burr sweeping process is done across shop floor but these manual deburring areas are always filled with fine dust particles in air leading to health issues of entire workforce, specialized deburring cells takes care of these environmental and 5S issues.