JUKI UT55 User manual

INSTRUCTION MANUAL
MF-7900(D)/UT55,56,57

i
CONTENTS
I. SPECIFICATIONS...........................................................................................................1
II. AT THE BEGINNING......................................................................................................1
III. INSTALLING THE ACCESSORIES.............................................................................2
1. Installing the presser lifting cylinder ............................................................................................ 2
2. Installing the air regulator .............................................................................................................. 2
3. Installation and setting SC-921...................................................................................................... 3
(1) Installing the SC-921 on the table ( Table-mount type ) ............................................................................3
(2) Installing the SC-921 on the table ( Semi-submerged type ) ....................................................................3
(3) Connecting the cords...................................................................................................................................4
(4) Setting procedure of the machine head .....................................................................................................5
(5) Setting the lower stop position of the needle bar .....................................................................................6
IV. AIR PIPING DRAWING.................................................................................................7
1. Piping of the thread trimmer device (UT57).................................................................................. 7
2. Piping of the thread trimmer device (UT55).................................................................................. 8
3. Piping drawing for air blow (UT56)................................................................................................ 9
4. Adjusting the air regulator ............................................................................................................. 9
V. THREADING THE MACHINE HEAD..........................................................................10
VI. ADJUSTING THE LOOPER THREAD TRIMMER MECHANISM...........................11
1. Adjusting the thread trimmer air cylinder....................................................................................11
2. Adjusting the Lower knife ............................................................................................................ 12
3. Adjusting the position of clamp pressure adjusting spring ..................................................... 12
4. Adjusting the knife engagement and the knife pressure adjusting spring ............................. 12
5. Adjusting the pressure of clamp spring ..................................................................................... 12
6. Initial position of the looper thread trimmer mechanism.......................................................... 13
7. Adjusting the stopper ................................................................................................................... 13
8. Adjusting the height of the lower knife....................................................................................... 13
9. Adjusting the lower knife holder guide....................................................................................... 13
10. Adjusting the longitudinal position of the blade point of lower knife...................................... 14
11. Adjusting the thread trimmer sensor .......................................................................................... 14
12. Adjusting the speed of looper thread trimmer ........................................................................... 14
VII. ADJUSTING THE THREAD RELEASE MECHANISM ..........................................15
1. Adjusting the disk-rise ................................................................................................................. 15
2. Adjusting the thread release hook .............................................................................................. 15
VIII. ADJUSTING THE TOP COVERING THREAD TRIMMER MECHANISM............16
1. Adjusting the engagement of knives .......................................................................................... 16
2. Adjusting the pressure of clamp spring ..................................................................................... 16
3. Adjusting the position of the blade point of moving knife........................................................ 16
4. Adjusting the speed of moving knife .......................................................................................... 17
IX. ADJUSTING THE AIR-BLOW WIPER (UT56) .........................................................18
1. Installing the air-blow wiper......................................................................................................... 18
2. Adjusting the air-blow wiper ........................................................................................................ 18
X. ADJUSTING THE NEEDLE THREAD WIPER (UT55)..............................................19
1. Adjusting the clamp spring.......................................................................................................... 19
2. Installing the needle thread wiper ............................................................................................... 19
XI. MAINTENANCE..........................................................................................................20
1. Cleaning the motor fan ................................................................................................................. 20

– 1 –
I. SPECIFICATIONS
Model name High-speed, cylinder-bed coverstitch machine Semi-dry head, high-speed, cylinder-bed
coverstitch machine
Model MF-7900 series MF-7900D series
Stitch type ISO standard 406, 407, 602, and 605
Example of application Hemming and covering for knits and general knitted fabrics
Sewing speed Max. 6,500 sti/min (at the time of intermittent operation)
V-belt type
Max. 6,000 sti/min (at the time of intermittent operation)
Direct-drive type
Speed of stitch at the delivery:
4,500 sti/min (at the time of intermittent operation)
Max. 5,000 sti/min (at the time of intermittent operation)
V-belt type
Max. 5,000 sti/min (at the time of intermittent operation)
Direct-drive type
Speed of stitch at the delivery:
4,000 sti/min (at the time of intermittent operation)
Needle gauge 3-needle ..... 5.6 mm and 6.4 mm
2-needle ..... 3.2 mm, 4.0 mm and 4.8 mm
Di󰀨erential feed ratio 1 : 0.9 to 1 : 1.8 (stitch length : less than 2.5 mm)
(1 : 0.6 to 1 :1 .1, when the di󰀨erential link hinge screw is changed)
Micro-di󰀨erential feed adjustment mechanism is provided. (Micro-adjustment)
Stitch length 0.9 mm to 3.6 mm (can be adjusted up to 4.5 mm)
Needle UY128GAS #9S to #14S (standard #10S) UY128GAS #9S to #12S (standard #10S)
Needle bar stroke 31mm (33 mm when the eccentric pin is changed over)
Dimensions (Height) 450 x (Width) 456 x (Length) 299
Weight 45 kg (With pneumatic type thread trimmer) , 42 kg
Lift of presser foot 8 mm (needle gauge : 5.6 mm without top covering), and 5 mm (with top covering)
Micro-lifter mechanism is provided.
Feed adjustment
method
Main feed............... dial type stitch pitch adjustment method
Di󰀨erential feed ..... lever adjustment method (micro-adjustment mechanism is provided.)
Looper mechanism Spherical rod drive method
Lubricating system Forced lubrication method by gear pump
Lubricating oil JUKI GENUINE OIL 18
Oil reservoir capacity Oil gauge lower line : 600 cc to upper line : 900 cc
Installation Table-mount type, Semi-submerged type
Noise - Equivalent continuous emission sound pressure level
(LpA) at the workstation:
A-weighted value of 79.5 dB; (Includes KpA = 2.5 dB);
according to ISO 10821- C.6.2 -ISO 11204 GR2 at
4,500 sti/min.
- Equivalent continuous emission sound pressure level
(LpA) at the workstation:
A-weighted value of 76.5 dB; (Includes KpA = 2.5 dB);
according to ISO 10821- C.6.2 -ISO 11204 GR2 at
4,000 sti/min.
Remove xed band ❶for transportation before setting
up the sewing machine.
II. AT THE BEGINNING
❶

– 2 –
❶
❷
❺
❹
B
A
❸
1. Installing the presser lifting cylinder
III. INSTALLING THE ACCESSORIES
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power o󰀨 and ascertaining that the motor is at rest.
1) Install presser lifting cylinder asm. ❶to the sewing
machine with screws ❸, washers ❹and spring
washers ❼.
2) Tighten screw ❸in such manner that a clearance
of 1 to 2 mm is provided between cap ❾at the top
end of presser lifting cylinder asm. ❶and presser
lifting lever ❷.
If the clearance cannot be adjusted to 1 to 2 mm,
adjust the height of nut ❽and cap ❾to obtain the
correct clearance between the cap and lever.
3) Adjust the height of screw ❺referring to the
Instruction Manual for MF-7900 (VI-14. Adjusting
the presser foot lift), and tighten nut ❻.
4) Stroke of cylinder asm. ❶is 30 mm. Make sure
that presser lifting lever ❷comes in contact with
screw ❺within the range of cylinder stroke.
1) Install pressure gauge ❺to regulator main body ❶.
2) Attach joint ❸to air intake port A, and joint ❹to
exhaust port B.
3) Install air regulator main body ❶under the table
with wood screw ❷.
2. Installing the air regulator
❶
❷
❸
❹,❼
❺
❻
1 to 2mm
❽
❾

– 3 –
* The instructions apply to the case the control box is installed on the table of the MF-7900(D).
To use any other machine head, install the control box on the table referring to the Instruction Manual for the
main body of the relevant sewing machine.
1) Install control box ❷on the table with mounting bolt asm. ❶supplied with the unit.
At this time, insert the nuts and washers supplied with the unit as illustrated in Figure Aso that the support
plates and the control box ❷ are securely xed.
2) Install the control box ❷(or the one equipped with a small sized motor unit) on the table. Then, install the
sewing machine head on the table. (Refer to the Instruction Manual for the sewing machine.)
3) Install the mounting plate on the CP-18 panel ❺with four tapping screws ❹supplied with the unit.
At this time, take care not to allow the cable to be caught under the mounting bracket.
(Install the CP-18 on the table as illustrated in Fig. B.)
4) Install CP-18 panel ❺on the table with wood screw ❻.
1) Install right and left support plates ❼and two
rubber seats ❽of the respective support plates.
2) Install control box mounting plate ❾on the
control box with four screws 󱢳.
3) Install the parts assembled in Step 2) on the
underside of support plates ❼with four screws
󱢴.
4) Install support plates ❼and the control box
❷on the table with mounting bolts asm. ❶
supplied with the unit. At this time, insert the
nuts and washers supplied with the unit as
illustrated in Figure Aso that the support plates
and the control box ❷ are securely xed.
* The steps of procedure from the next one and
beyond are same with those for the table-xed
type machine head.
(1) Installing the SC-921 on the table ( Table-mount type )
3. Installation and setting SC-921
(2) Installing the SC-921 on the table ( Semi-submerged type )
❶
❷
❻
❺
Convex
washer
Spring
washer Hexagonal nut
Fig. A
❹
❻
Fig. B
❶
❾
󱢳
❼
❽
󱢴
❶
❷

– 4 –
(3) Connecting the cords
1) Pass cords ❶of the thread trimming solenoid,
reverse-stitching solenoid, etc. and the cord from
the motor through hole Ain the table to route them
down under the machine table.
2) Loosen screw Bin cover ❷with a screwdriver to
open the cover.
3) Connect 14P code ❸coming
from the machine head to
connector ❻(CN36).
4) Insert 3P cord ❾coming
from the machine head into
connector 󱢳(CN42).
5) Insert presser foot lifter cord 2P
❹into connector ❼(CN37).
6) Connect connector ❺coming
from the motor to connector ❽
(CN30) on the circuit board.
7) Insert pedal sensor cable 󱢴into connector 󱢵(CN34).
8) Insert motor fan cord 󱢶into connector 󱢷.
[Connecting the connector for the operation panel]
Be sure to turn OFF the power before con-
necting the connector.
Be sure to securely insert the respective connectors after checking the inserting directions since all con-
nectors have the inserting directions. (When using a type with lock, insert the connectors until they go to
the lock.) The sewing machine is not actuated unless the connectors are inserted properly. In addition, not
only the problem of error warning or the like occurs, but also the sewing machine and the control box are
damaged.
The connector for the operation panel is provided.
Paying attention to the orientation of the connector 󱢸,
connect it to connector (CN38) 󱢹located on the circuit
board. After the insertion, securely lock the connectors
to prevent them from coming o󰀨 easily.
󱢸
󱢹
❼
❹
❺
❽
❸
❻
❾
󱢵󱢳
󱢴
󱢶
󱢷
❶
A
❷
B

– 5 –
❹
❸❷❶
❹
❸❷❶
❹
❸❷❶ Type of machine head Model name
F79
MF-7900/UT55
MF-7900/UT56
MF-7900/UT57
F79d
MF-7900D/UT55
MF-7900D/UT56
MF-7900D/UT57
(4) Setting procedure of the machine head
For the operation panel other than CP-18, refer to the Instruction Manual for the operation panel to be used
for the setting procedure of the machine head.
1) Call function setting No. 95.
2) The type of machine head can be se-
lected by pressing switch
❸
(
switch
❹
).
* Refer to the "MACHINE HEAD
LIST" on the separate sheet or the
Instruction Manual for the machine
head of your sewing machine for the
type of the machine head.
3) After selecting the type of machine
head, by pressing switch ❶(
switch ❷), the step proceeds to 96
or 94, and the display automatically
changes to the contents of the
setting corresponding with the type of
machine head.

– 6 –
❹
❸❷❶
Fig. 1
(5) Setting the lower stop position of the needle bar
Call function setting No. 122. Check to
be sure that the lower stop position of the
needle bar is as shown in Fig. 1. If not,
adjust the lower stop position of the nee-
dle bar properly using function setting No.
122. (Adjustment can be made within the
range of ±15°).

– 7 –
IV. AIR PIPING DRAWING
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power o󰀨 and ascertaining that the motor is at rest. In addition, cut the air
supply from air compressor.
1. Piping of the thread trimmer device (UT57)
⑪
③
④
⑨
①
②
⑩
⑨
⑩
⑪
󰽈
⑨
⑪

– 8 –
2. Piping of the thread trimmer device (UT55)
③
④
󰽈󰽈
⑨⑨
⑪