FORM-2
THE PATENTS ACT, 1970
COMPLETE SPECIFICATION
(SECTION -10)
An improved household mixer grinder with blade, means of enhanced life of operation.
BAJAJ ELECTRICALS LIMITED, a company incorporated under the Indian Companies Act, 1956, having its registered office at 45/47, Veer Nariman Road, Mumbai-400 001, Maharashtra, India.
An Indian Company
The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed: -
TECHNICAL FIELD:
The invention relates to improvement in the life of cutting blade used in mixer grinders for domestic kitchen use. The cutting blades in mixer grinder are used for different applications. Based on applications, various shapes and sizes of the

blades are used. The blades are made of stainless steel with sharp cutting edges on one side and blunt edge on another side. The blade rotates in motion such that sharp side is facing the material to be cut or ground. It is observed that after repeated operations of use, the sharp edge wears out and becomes blunt thereby affecting the fineness of grinding and cutting. The invention proposed is use of titanium nitride coating over the stainless steel blade. This coating imparts wear resistance and hardness to the blade. The hard and wear resistant blade can withstand more working cycles as compared to uncoated blades.
BACKGROUND ART:
Standard Existing configuration and the working principle involved in standard existing product: see fig 1
The standard existing configuration consists of a blade in mixer grinder jar, fit to the spindle shaft through blade nut. Blade nut is screw fit to the spindle shaft. The spindle shaft is connected to coupler at the lower end.
The spindle shaft is guided through bush. The bush is press fit in the insert. Insert is mounted on jar base. The jar is having holes through which screws are used to engage it with insert. The jar base gets sandwiched between jar and insert.
Please refer fig 2 for typical blade design. The elements of blade are explained. The shapes of blade vary based on applications while elements_remain the same.

One edge of the blade is made sharp. The direction of rotation is such that the sharp edge is on front side. The rotation of blade forces the sharp edge against the ingredients in the jar. The sharp edge cuts the ingredients to fine particles. The mixer blade rotates with almost 16000 to 20000 rpm when operated at maximum speed. With this high rpm, the blade gets enough momentum almost to grind turmeric sticks to powder.
While the blade cuts various types of ingredients, its surface is continuously subjected to friction and heating. This high temperature friction causes the sharp edge to continuously erode. Over a long period of usage, the sharp edge turns blunt affecting the grinding process and outcome. For example, in some cases, the blade may not make turmeric powder with the same fineness as it used to make in the beginning. At such times, customers have to replace this old blunt blade with new sharp blade.
OBJECT OF THE INVENTION :
The object of the present invention is enhance the life of the mixer grinder blades by coating it with food grade titanium nitride surface coating, thereby improving the wear resistance of the blade material.
THE STATEMENT OF INVENTION :
Accordingly the invention provides an improved household mixer grinder with blade means of enhanced life of operation used for grinding, cutting, chopping, mincing, blending, the ingredients of food and juice making configuration consists of a blade in mixer grinder jar, fit to the spindle shaft through blade

nut; the said blade nut is screw fit to the spindle shaft; the said spindle shaft connected to coupler at the lower end; the said spindle shaft guided through a bush press fitted in the insert mounted on jar base having holes through which screws engaged the said insert; the said jar base gets sandwiched between jar and insert; characterized in that the said blade means surface coated with titanium nitride.
SUMMARY OF THE INVENTION:
Titanium nitride coating application imparts surface hardness to the blade. Harder blade means, it can run for more number of grinding cycles giving good fine grinding performance each time.
BRIEF DESCRIPTION OF DRAWINGS:
Fig 1: Shows the cross sectional view of the mixer grinder jar with components Fig 2 : Shows the blade design, its cutting edge and direction of rotation Fig 3: Shows typical coating process.
DETAILED DESCRIPTION OF THE INVENTION:
Referring to figures 1 and 2 which show the constructional features of mixer grinder known in the prior art. The prior art draw back problem is solved by improving the quality of blade means of mixer grinder. The strength of the said blade means enhanced by almost 100% by coating with titanium nitride. The

blade means include different type blades used in grinder cum mixer for grinding, cutting, chopping, mincing, blending, the ingredients of food and juice making configuration. The process of titanium nitride thin coating on the blade means as follows :-
Now referring figure 3, illustrates the process of physical vapour deposition. The high vacuum chamber is having titanium nitride vapour spray. The mixer blade means placed on a support connected to negative electrical and chamber is earthed.
Titanium nitride coating is applied on the blade surface by means of Physical Vapor Deposition (PVD). This process is characterized by the creation of a metal vapor that can be reacted with different gases to form a thin film coating. The said gases include nitrogen, argon, hydrogen are used. The most common PVD methods used today are arc deposition and sputtering. Both processes are carried out under high vacuum conditions within a coating chamber.
Due to creation of film on the blade, the surface of blade becomes hard and wear-resistant. Typically the coating thickness for this application is in the range of 2 to 4 microns.
With application of this coating the hardness of the parent material surface increases by almost 100%. ( For instance, if Vickers hardness number for parent material i.e. stainless steel is 475, after coating, the same hardness is observed to be above 900)

With higher hardness of surface, the tendency of the blade to wear is low. Hence it can last almost twice the number of grinding cycles.
ADVANTAGES OF INVENTION
1. A titanium coated blade for use in mixer grinder, food processors, hand blenders, liquidizers
2. Improved surface hardness of the blade due to this coating
3. Improved wear resistance
4. Consistency of grinding performance over more number of grinding cycles.

WE CLAIM:
1. An improved household mixer grinder, with blade means of enhanced life of operation, used for grinding, cutting, chopping, mincing, blending, the ingredients of food and juice making configuration consists of a blade in mixer grinder jar, fit to the spindle shaft through blade nut; the said blade nut is screw fit to the spindle shaft; the said spindle shaft connected to coupler at the lower end; the said spindle shaft guided through a bush press fitted in the insert mounted on jar base having holes through which screws engaged the said insert; the said jar base gets sandwiched between jar and insert; characterized in that the said blade means surface coated with titanium nitride.
2. An improved household mixer grinder as claimed in claim 1 wherein Typically the said titanium nitride coating thickness for blade in the range of 2 to 4 microns.
3. An improved household mixer grinder as claimed in claims 1 and 2 wherein the surface hardness of the coating blade increases by almost 100% Vickers hardness number.
4. A process for titanium nitride coating on blade means for improved household mixer grinder used for grinding, cutting, chopping, mincing, blending, the ingredients of food and juice making configuration as claimed in claims 1 to 3 comprises applying titanium nitride coating on the blade surface by means of Physical Vapor Deposition (PVD) by the creation of a metal vapor that reacted with different reactive gases to form a thin film coating.

5. A process as claimed in claim 4 wherein the said Physical Vapor Deposit (PVD) methods used today are arc deposition carried out in high vacuum conditions within a coating chamber.
6. A process as claimed in claim 4 wherein the said Physical Vapor Deposition is a sputtering carried out in high vacuum conditions within a coating chamber.
7. A process as claimed in claims 4 to 6 wherein the said gases are nitrogen, hydrogen and argon.