INFLUENCE OF FECL 3 ON MATERIAL REMOVAL RATE AND SURFACE ROUGHNESS IN CHEMICAL MACHINING PROCESS

Non-traditional machining process is more used to manufacture geometrically complicated and an accurate parts for electronics, aerospace and automotive industries. Chemical machining process is one of non-traditional machining methods, it is as well named as chemical etching. The current research is aimed to study the influence of the machining time, machining temperature, etching solution concentration on the material removal rate and surface roughness of aluminum alloy by using mix of acid FeCl 3 . There are three of machining temperatures (25, 30 and 35 ºC) with three machining times (4, 8, and 12min) and etching solution concentration (25%, 50%, and 75%) were used as machining conditions. These conditions are significant variables that have effect on finishing performance of chemically machined aluminum alloy. Machining time has the greatest effect among these variables. The time is the most important parameter for maximum Material Removal Rate (MRR), and the interaction between temperature and etchant concentration is the next important parameter for maximum MRR. The time is the greatest parameter for minimum Ra, the interaction between time and temperature is the next significant parameter for less Ra. for the micro-protuberance. This study illustrate increasing concentration with increase of micro-protuberance. Water includes in low concentration etchant effects


INTRODUCTION
Non-traditional machining process is widely used to produce geometrically difficult and exactitude parts from materials in different industries as aerospace, electronics and automotive manufacturing (McGeough, 1988). Many machined elements need to dimensional accuracy and high surface finish, special size and complex shape which cannot be performed with the conventional machining processes (Benedict, 1987). Non traditional machining process is recognize as a group of operations that remove surplus material by different techniques including mechanical, electrical, chemical or thermal energy or combinations of these energies but don't use a sharp cutting tools as it required to be using for traditional manufacturing processes. Exceedingly brittle and hard materials are hard to machine by conventional machining processes such as turning, drilling, milling and shaping (Çakır et al., 2005). Nontraditional machining processes, as well called advanced manufacturing processes, are used where conventional machining processes aren't suitable, satisfactory or economical due to special reasons as outlined below:  Easy clamping of the brittle and fragile materials.
 Flexibility in workpiece machining.
 Machining the complicated shape.
There are many types of non-conventional machining process have been advanced to meet extra needed machining conditions. When these operations are used correctly, they show many features over non-conventional machining processes (Nesreen 2016). Chemical machining explain practically unlimited field for engineering and design intelligence, to win the most from its unrivaled characteristics, it must be approach with the thought that this industrial tool can do jobs not practical or potential with another metal working methods (Cakir, 2008). Chemical Machining (CHM) applications field from large aluminum aircraft wing parts to tiny integrated circuit chips. The actual depth of cut ranges between 2.54 to 12.27mm. In large thin sheets that have shallow cuts are of the most common application particularly in weight reduction of aerospace elements. Various designs maybe machined from the same sheets at the same time."(CHM) is used to thin out walls grids and ribs of part that have been produced by forging,

Workpiece material
The chemical composition of aluminum alloy is shown in the

Etchant Solution
The FeCl3 etchant was used with three concentrations, as shown in the Table 2.

Samples preparation
1-Basic material: Al Zn Mg Cu 1.5DW 1725-1 alloy sheet was cut to samples with dimensions of (30x30x1 mm).

2-Preparation of the samples for CHM:
Firstly, the sample was cleaned from the dust, oils and rust by using maskant material with alcohol (ethanol 98%) then it was dried with dryer of air then swill with water and dry"with air"dryer"again. A specially designed glass bowl was used to carry out the coating of the samples. Vaseline was used to ease removing the sample from the mold. Mixing (5) of polymer with (0.25) of accelerator. After decant the"polymeric masking"material,"the bowl was"kept"in room at 25ºC"for 60 min for"drying."Only one"face"of samples was left"without"coating."This face"represents"the part to"be chemically"machined." A"hole diameter of 2mm was"drilled in all samples for purpose of holding inside of"the etchant"solution by using tongs of plastic through the machining"process, workpiece before and after machining in Fig. 1 is given bellow.

Masking material
Basic alloy Basic alloy 48 Abbas F. Ibrahim et al.

System of chemical machining.
A magnetic stirrer thermostat was used to achieve the machining process. It is included a thermostat in order to set the temperature parameter of etchant and velocity controller during the machining process; Fig. 2 is showing it.

Measuring devices
The metal removal rate (MRR) was calculated experimentally by (Mettler Toledo Analytical Balance Sensitive weighing) with accuracy ±0.0001, and measuring the weight difference before and after the machining. The surface roughness roughness (Ra) was measured by using

EXPERIMENT ANALYSIS
The  Results of the experimental were then turned to a signal to noise ratio (S/N), determination the features of quality deviate from"or"nearing to the required value. There are three of quality categories feature"in"the"analysis"of"the"S/N"ratio, i.e. , Nominal"is"the better , the lower is the"better"and"higher"is"the"better.
The"equation applied for"calculating signal-to-noise ratio"for getting the"smallest"Ra"is: The characteristic of quality for MRR higher is the better type. Therefore, the S/N ratio is given Where n: is the number"of the"replications.
yi: spotted value of"response

RESULTS AND DISCUSSION
In the Table 4 show the results of the experiment and indicated to the material removal rate

CONCLUSIONS
The current study has reached to the below conclusions: