Presentation Grinding Machine

GRINDING MACHINE
“MANUFACTURING PROCESSES
Name : Eka setia budi
Class: 2b
Grinding Machine
Grinding is an abrasive machining process done with the help of revolving wheel mounted on a sutable Machine. Abrasive machning processes are used under one or more of the following conditions.
1. The material to be cut is too hard for other machining  processes.
2. The surface finish desired is superior to what can be obtained with other methods.
3.The dimensional accuracy requirements are too stringent for other processes.
Two characteristics features of the abrasive machining a given surface, each taking a minute of cut of its own and that the geometry and orientation of these cuting edges at any given instance are completely random.
- It is the only economical method of cuting hard meterila hardened steel.
- It produces very smooth surfaec, suitable for bearing surface.
- Surface pressure is minimum n grinding.It is suitable for light work,which will spring away from the cutting tool in the othe machining processes.
Grinding Pocesses
Abrasives
Abrasives are hard subtances wth adequate toughnes capable of machining materials too hard to be cut by most other tool materials.
They can also produce better surface finish and closer dimensional tolerances on most materials.They can be used in the machining processes as loose grains,in the form of grinding wheels and sicks or as coatings depending upon the type of operations.
TYPES OF ABRASIVE
1. Natural Abrasive
2. Artifical Abrasive
Types of abrasives
1. Aluminimium oxide
Aluminium axide may have varitation in properties arising out of differences in chemical compossion and structure associated with the manufacturing process. Pure Al2O3  grit with defect stucture like voids leads to unusually sharp free cutting action with low strength and is advantageous in fine tool grinding operation,and heat sensitive operations on hard,ferrous materials. Reular or brown aluminium oxide (doppe with TiO2) processes lower hardness and higher toughness than whte Al2O3  and is recommended heavy duty grinding to semi finishing.
Al2O3  alloyed with chromium oxide kurang dari 3% is pink in colour. Monocrystalline Al2O3  Grits make a balance between hardness and thoughness and thoughness and are efficient in medium pressure  heat senitive operation on ferrous materials.
Microcrycristalline Al2O3  grits of enchanced toughes are pratically suitable for stock removal grinding. Al2O3  Alloyed  with zirconia also makes extremely tough grit mostly suitably for high pressure, high material removal grinding on ferrous material an are not recommended for pression grinding. Microcrystalline sintered Al2O3  Grit is the latest development particualarlyk known for is thougnes and self sharpening characteristics.
2. cBN (cubic broon nitride)
Diamonds thoug hardest is not suitable for grinding ferrous materials bescause of its reactivity. In contrast, cBN the second hardest material, because of chemical stability is the abrasive material of choice for efficient grinding of HSS, alloy steels HSTR alloys.
Grain Size
The number indicating the size of the girl represent the number of openings in the seive used to size the grain.The larger the grt size number the finer the grit.
Grade
- Grade indicates the strength of the bond and, therefore  the “hardness” of the wheel.
- In a hard wheel the bond is strong and securely anchor the grit in place, and therefore, reduces the rate of wear.
- In a soft wheel,the bond is a weak and the girl is easily detached resulting in a high rate of wear.
Structure
This indicates the amount of bond present between the individual abrasive grains,and the closeness of the individual grain to each other. An open structured wheel will cut more freely.That is, it will remove more metal In a given time and produce less heat.
BOND
Vitrified bond (V)
Silicae bond (S)
Shellac bond (E)
Rubber bond (R)
Resionoid bond (B)
SELECTION OF GRINDING WHELL
For grinding a job the right grinding wheel is to be selected. The selection of a grinding wheel will depend on the following factors
-Material to be ground
-Amount of stock to removed
-Finish required
-Area of contact
-Wheel speed
-Personal factor
-Method of cooling
Type of grit used for grinding
Depth of cut
- It is the thickness of the material removed in surface grinding for one cut
- Depth of cut in grinding depend on the :
- Cuting load
- Power of the mahine
- Finish required
WORK SPEED
SURFACE GRINDING
- It is precision grinding machine to produce flat surface on workpiece. It is a more economical and more practical method of accurately finishing flat surface than filling and scraping.
- TYPES OF SURFACE GRINDERS
- Horizontal spindle reciprocating table
-     Horizontal spindle rotary table
- Vertical spindle reciprocatingtable
- Vertical spibdle rotary table
CENTERLESS GRINDING MACHINE
- A centerless grinding machine as the name suggest has no centers, drivers and othe fixtures required for holding the workpiece.
- It used for grinding external cylindricsl surfaces, tapers and forms with rotational symmetry.
- The essential units of the machine are the grinding wheel, the regulating wheel. The work rest blade and the side.
- The regulating wheel and work rest blade support the work piece
- The work rest blade and the regulating wheel slide are mounted yet on another  slide which is moved towards the grinding wheel for depth motion or in feed.
Advanced of centerless grinding
- Due to shorther loading times, actual grinding time is decreased compared with other mtehods of grinding .once the centerless grinder has been properly set-up for a particular run. No further adjustment or addiotional set-up for a particular run, No further adjustment or addictional set-up are needed as opposed to centertype (cylender) grinding.
- This alone offers subtansial savings. The workpiece is under constant, rigid support while in the grinding mode, making it feasible to take heavier cuts and grind fine puns, rods and wires.
- Centerless machines are designed for simplicity which in itself cuts down on machine maintenance
Thank you . . . .

Past presentense

1. Kalimat Nominal (Nominal Sentence)
Kalimat Nominal (Nominal Sentence) adalah kalimat yang predikatnya bukan kata kerja atau dengan kata lain kalimat nominal adalah kalimat yang predikatnya berupa tobe. Penggunaan tobe ini tergantung dari penggunaan tenses dan tergantung dari Subjek kalimatnya (jamak atau tunggal). Jika kalimat tersebut adalah kalimat Simple Present Tense maka tobe yang harus digunakan adalah AM, IS dan ARE. Tobe bisa diartikan adalah atau bisa juga tidak diartikan, tobe muncul karena tidak ada Verb (kata kerja) dalam kalimat. Mari kita lihat contohnya dalam kalimat dibawah ini:
Contoh present time
I am in class today,Alice I at the library today
Contoh past time
I was an yesterday,Alice was at the library yesterday
Contoh Negative
I was not in class yesterday, I wasn’t in calss yesterday
Contoh Negative Contraction
I was not in class yesterday, I wasn’t in class yesterday
Time Expression
Today -> Yesterday
Question
Were you in class yesterday? -> Yes, I was/ No I wasn’t
Dari contoh kalimat di atas semua kalimat tidak mengandung kata kerja melainkan menggunakan tobe yang disesuaikan dengan tensesnya dan subjek dalam kalimatnya. Dan biasanya tobe diikuti kata selain kata kerja (verb) contohnya: kata benda (noun) seperti student, soldier; kata sifat (adjective) seperti: beautiful, clever dan kata keterangan (adverb) seperti: the classroom, the kitchen. Sehingga dengan demikian kalimat tersebut disebut kalimat nominal (nominal sentence).




2. Kalimat Verbal (Verbal Sentence) adalah kalimat yang mengandung kata kerja (verb), atau
dengan kata lain kalimat verbal itu adalah kalimat yang predikatnya adalah kata kerja (verb). Sebagai contoh adalah kalimat dalam Simple Present Tense:
(+) S + V2 + O
(-) S + did + Not + V1 + O
(?) Did + S + V1 + O
Did -> I,you,they,we,she,it
Examples :
a. I walk to school every day
b. I walked to school yesterday
Irregular Verbs
Present  - Pat
 Contoh :
Do – did
Eat – ate
Get - got
Dari contoh kalimat diatas dapat kita simpulkan bahwa semua kalimat diatas menggunakan kata kerja (verb) sebagai predikatnya
Demikian sedikit perbedaan kalimat verbal dan nominal dalam bahasa Inggris. Dan dapat disimpulkan bahwa dalam kalimat bahasa Inggris jika suatu kalimat sudah menggunakan verb maka tidak menggunakan tobe begitu juga sebaliknya jika kalimat tersebut menggunakan tobe maka tidak ada verb didalamnya. Tetapi dalam beberapa kasus terdapat kalimat yang didalamnya menggunakan tobe dan verb secara bersamaan tetapi itu akan merubah arti kalimat tersebut dan itu akan dibahas di penjelasan berikutnya.

3. Past progressive -> an acivity in progress at a particular time in the past
(+) S + tobe (was,were) + V-ing + O
(-) S + tobe +not V-ing + O
(?) tobe + S + V-ing + O?

Karena ini adalah bentuk past jadi tobenya dalam bentuk was atau were

Was -> I,he,she,it
Were -> we, you, they
Examples ;
 (+) we were studying english
(-) we were not (weren’t) studying english
(?) Were we studying English ?
Jika belajar bahas inggris arus memperhatikan waktu dengan menggunakan past progressive, jadi semua kata kerja semua tenses adalah progressive menggunakan V-ing.
4. Simple Future -> Future ( masa yang akan datang)
a. Be going to ( digunakan untuk memprediksi suatu hal di masa yang akan datang dan sudah terencana)
Be going to
Rumus:
- (+) S + tobe (Ia,am,are) + going + to + V1 + O
- (-) S + tobe + not + going + to + V1 + O
- (?) tobe + S + going + to + V1 + O?
Contoh ;
I am going to leave at 9.am tomorrow morning
I am not going to leave at 9.am tomorrow morning
Am I going to leave at 9.am tomorrow morning ?

b. Will ( digunakan suatu hal yang tidak direncanakan, missal akan membantu teman yang sulit untuk mengerjakan tugas kita bisa menggunakan kata will).
Rumus :
(+) S + will + V1 + O
(-) S + will + not + V1 + O
(?) will + S + V1 + O?
Contoh;
I will study hard
I will not (won’t) study hard
Will I study hard ?

   Penggunaan keduanya bisa digunakan untuk future prediction (memprediksi suatu hal di masa yang akan datang.

Be going to Will
a. She is going to succeed because she works hard
b. She will succed because she works hard. Be going to and well mean the same when they are used to make predictions about the future a). and b) have the same meaning.
c. I bought some wood because I am going to build aa bookcase for my apartement. Be going to (but not will) is used to express a prio plane (I,e,a plan made before the moment of speaking). In  ( c) the speaker plans to build a bookcase.
d. This  chair s this to heavy for you to carry alone Will (but bot be going to) is used to express a deision the peaaker makes at the moment of speaking. (d) the speaker dicides to help at the immediate present moment he did not have aprion plaan or intention to help.

A dan B digunakan untuk memprediksi maka she (dia) akan sukses dimasa yang akan datang karena bekerja keras
C.  Be going to digunakan untuk menyatakan rencana kita yang sudah matang, missal kita punya rencana setelah lulus dari kuliah ini ( I going to continue my study) contoh dari will missal kita mengobrol dengan teman lalu kita mebantu mengerjakan tugasnya kita gunakan will  ( I will help you)
Kalau future gunakan tomorrow,next,in
Demikian rangkuman yang saya buat berdasarkan materi yang disampaikan tentang Past presentense.

Simple presentense

Simple presentense