Section 2 - The Break System

Question 1

Where is the Break system

Answer 1

at the beginning of the milling process

Question 2

Object of the earlier break system?

Answer 2

To shear open the wheat and scrape away the endosperm from the bran skin in large particles
Bran is left as large flat flakes

Question 3

What is the object of the break system on later breaks

Answer 3

To scrape the remaining endosperm off the wheat skin as cleanly as possible, avoiding any cutting up of the bran

Question 4

What affects the length of the break system

Answer 4

The types of wheat to be used, flour specifications, mill performance

Question 5

How many break passages are used

Answer 5

used to be 4, with introduction of softer wheats, now 5 (soft is more difficult to clean)

Question 6

What do break rolls do

Answer 6

Break open and scrape the wheat grains to release endosperm

Question 7

How many break stages are used?

Answer 7

Between 3 and 9, in the UK 4 or 5

Question 8

Do roll flutes get finer or coarser with each stage?

Answer 8

Finer

Question 9

What are more finely fluted rolls known as

Answer 9

Scratch rolls

Question 10

Where are bran finishers installed

Answer 10

After later break rolls

Question 11

What is the aim of the break system

Answer 11

To achieve maximum release of endosperm particles as semolina and middlings without disintegration of wheat skin or bran

Question 12

How is the most suitable flute configuration, roll diameters, speeds, differentials and grooving spirals determined

Answer 12

Experience!

Question 13

Can bran powder be separated from flour?

Answer 13

No - wheat skins should be kept as whole as possible through the break system

Question 14

What does the extent to which the endosperm is scraped off the bran depend on

Answer 14

Type of wheat
Condition of wheat
Flour extraction and product specification required
Design of fluting on rolls
Adjustment of rolls

Question 15

How is break roll surface measured

Answer 15

mm/100kg of wheat ground/24 hours

Question 16

What is the general surface allocation of break systems

Answer 16

4-6mm/100kg/24h

Question 17

break roll surfaces on 1BK, 2BK, 3BK, 4BKC, 4BKF, 5BKF

Answer 17

1mm, 1mm, 1mm, 0.5mm, 0.5mm, 0.4mm (total 4.4mm)

Question 18

What alternative to rollermills can be used in break or reduction passages

Answer 18

Disc milling

Question 19

What is the main characteristic of disc milling

Answer 19

High productivity in relation to machines physical size and energy consumption

Question 20

Advantages of disc milling

Answer 20

compact
easily accessible and durable wearing parts
rapid disc and element replacement
accurate handwheel adjustment of grinding gap
large grinding surface gives high capacity and lower power consumption

Question 21

Disadvantages of disc milling

Answer 21

Higher temp of flour produced may damage flour enzymes
possible degradation in proteins of whole wheat flour
high temp of released particles reduces sieving efficiency
increased maintenance requirements caused by sweating in sifter sections

Question 22

What is the standard diameter for break/reduction rolls

Answer 22

250mm

Question 23

How long are the largest rolls and what breaks are they used on

Answer 23

1500mm, 1bk, 2bk, 3bk

Question 24

What size rolls do 4th and more breaks, scratch and reduction systems use

Answer 24

1000mm

Question 25

What are main rolls made of

Answer 25

Close-grained cast iron with hollow centre

Question 26

How many flutes per roll on 1bk, 2bk, 3bk, 4bk, 5bk

Answer 26

250-325, 400-450, 500-550, 675-750, 800-850

Question 27

What is the name of the flute profile that is most common

Answer 27

Saw tooth

Question 28

What size is the land

Answer 28

0.3-1mm

Question 29

What does the choice of flute profile depend on

Answer 29

Type of wheat to be ground Mill flow sheet Break release anticipated Results required

Question 30

How long is a flutes effective life

Answer 30

6-12months

Question 31

Draw a saw tooth flute profile

Question 32

What is the spiral on a break roll

Answer 32

1 in 50 (2%)

Question 33

Label the spiral on 1bk 2bk 3bk 4bkc 4bkf

Answer 33

1:50, 1:50, 1:24, 1:24, 1:24

Question 34

Which roll is run quicker?

Answer 34

The upper roll

Question 35

What is the ratio of speeds of rolls called

Answer 35

Differential

Question 36

How quick does the upper roll tend to go

Answer 36

550rpm

Question 37

What is the usual differential

Answer 37

2.5 : 1

Question 38

Draw the sharp sharp, sharp dull, dull sharp and dull dull arrangements

Question 39

How is the amount of material released at each break passage limited?

Answer 39

Adjusting the grind to a predetermined percentage release

Question 40

What do percentage release figures depend on

Answer 40

Length and type of system The grist Required spec of the finished products

Question 41

What are the typical break releases for 76% extraction

Answer 41

1bk - 40%, 2bk - 36%, 3bk - 6%, 4bk - 1.8%, 5bk - 0.45%

Question 42

What is the total release for 76% extraction

Answer 42

84.25%

Question 43

What is Bran finishing

Answer 43

The process by which remaining endosperm particles are detached from the bran and recovered as flour

Question 44

What is scalping

Answer 44

The separation of coarse overtails after any grinding operation, particularly the coarser bran fragments with endosperm still adhering after each break stage

Question 45

What happens to throughs from scalping sieves

Answer 45

Graded on further sieves into coarse and fine semolinas and middlings

Question 46

What happens to graded stocks

Answer 46

consigned to separate groups of purifiers according to particle size and quality

Question 47

What happens to dunst stocks

Answer 47

graded off and sent direct to lower reduction rolls

Question 48

What are all the separations from feed to flour?

Answer 48

coarse overtails -Coarse semolina -Medium semolina - Fine semolina - Coarse Middlings - Fine middlings - dunst flour

Question 49

What are the throughs of the first break rolls called

Answer 49

Break chop

Question 50

Where are bran finishers used

Answer 50

On coarse bran before third break and 4thbkc rolls, can also be used as final clean up after 5bk scalper.

Question 51

What affects efficiency of separation

Answer 51

Variations in flow or distortion of the range of particle size

Question 52

What affects capacity of sieving equipment

Answer 52

Moisture content of stocks - damp stocks do not flow well, sieving capacity is reduced and blockages can occur, too dry stocks have poor product quality

Question 53

In a pneumatic mill, what carries out the scalping, grading and dusting?

Answer 53

Plansifters

Question 54

What does variation in covers for scalping and grading depend on

Answer 54

Length of break system Whether coarse and fine stock are treated separately flute disposition and profile type of wheat to be milled

Question 55

What are the two golden rules for covers on scalping and grading

Answer 55

Break stock should always be free of pure semolina purifier stock should always be free from flour

Question 56

What is a good guide for calculating how much surface the break stock requires

Answer 56

half the total surface

Question 57

average sections for a 200 tonnes per day mill

Answer 57

1bk - 2 section 2bk - 2 sections 1&2 md - 1.5 sections 3bk - 2 sections 3md - 1 section 4bk - 2 sections 5bk - 1 section X - 0.5 sections reduction - 12 sections