Useful Datas For Tabletting Department
CLEANING OF PUNCH GUIDES AND DIE BORES
With the help of soft nylon / wire brass brush cleaning the punch guide holes and a die bore seat can clean. The turret should first be rotated by means of the hand-wheel until a punch and die bores are lined up with the lower punch-loading plughole. The bores should be cleaned in the following order.
a) Upper Punch Guide Bore.
b) Die Bore and Seat.
c) The Lower Punch Guide Bore.
When brushing the punch guide hole a cloth should be placed under the turret to collect dirt and prevent it entering the lower cams.
NOTE: If the die seats are not clean when a die is fitted, it may be found that the die is not level with the die table. The die must be removed, and the set cleaned before refitting the die. All punch and die bores should be thoroughly cleaned before fitting punches and dies.
FITTING DIES
The die should be cleaned (1) and the outside diameter lightly smeared with the oil used for punch lubrication (2)
hich is placed face downwards on the die table (3). The die is located centrally on the die pocket by a slight pressure with the finger on the top face of the die (4). This ensures that the die is perfectly square to the die pocket.
Once the die is located, the die bar (supplied in the tool kit).
Should be entered through the upper punch guide hole and allowed to drop onto the die face, three or four times, from a height of approximately 50mm to 75mm (2” - 3”). This is sufficient force to enter the die in the pocket.
Having entered the die more force can be applied by ramming the die with the die bar until the die is fully down on the seat of the die pocket. Additional force may be applied if necessary by hammering the top of the die bar.
5. FITTING THE DIE LOCK SCREWS
The Die Lock Screws have a curved spigot end and are fitted with a dowel pin to align the spigot with the recess in the periphery on the die.
The die lock screws should be lightly oiled on the thread and fitted into the die lock screw holes with the dowel located in the keyway of the die lock screw hole (1). Tighten the die screw using the Allen key supplied in the tool kit (2).
It Is Of The Utmost Importance That No Excessive Force Is Used In Tightening The Die Lock Screws (3 And 4).
A Maximum Load Of 194 Kg/Cm (14 Lbs/Ft) Should Not Be Exceeded To Prevent Distortion Of The Turret.A Maximum Load Of 194 Kg/Cm (14 Lbs/Ft) Should Not Be Exceeded To Prevent Distortion Of The Turret.
An extension of the Allen key supplied or a hammer must NOT be used as this can cause the turret to crack or distort the die bore (3 and 4).
After tightening the die lock screw check that the top face of the die has remained flush with die table.
If it should happen that a die rises in the die plate due to excessive tablet ejection loads, no amount of tightening of the die lock screws will prevent this.
NOTE: Further investigation should be made as to the cause of the excess force.
Assuming the die bores are not worn (barrelled - 5) it may be possible to reduce the ejection loads by adding more lubricant to the material being compressed or by using dies with specially manufactured tapered bores.
6. PUNCH HEIGHT ADJUSTMENT
Before fitting all the lower punches, fit one punch into a lower punch guide hole and rotate the turret until the lower punch rides up the ejection cam at the ejection point, on the right hand side of the machine. Check that the lower punch is perfectly flush with the die table at this point. If the punch is below the die plate this will result in the tablet being damaged at take off. If the punch protrudes above the die table damage to the punch tip and the underside of the force feeder base will result.
If shorter than standard, 133.65 mm long, or refaced punches are use it will be necessary to shim up the ejection cam until the punch is perfectly level with the die table. When standard length punches are refitted, it will be necessary to re-adjust the height of ejection cam. Adjustment of the ejection cam height is achieved by plastic shims being inserted or removed from under the ejection cam.
The ejection cam is secured to the cam platform from underneath by a socket head cap screw. An Allen key is supplied in the tool kit to fit these screws. After removal of the screws the plastic shims can be inserted or removed as required. Ensure that the socket head screw is replaced and the ejection cam is firmly locked down against the cam platform after fitting the plastic shims.
7. FITTING OF LOWER PUNCHES, INCLUDING LUBRICATION AND PUNCH HOLDING DEVICE.
To prevent punch flight and also double embossing, friction is applied to the punch shank by means of a Nylon Plug, held by a flat spring. It is essential that these nylon plugs be fitted for correct running. When fitting lower punches, the round head screws holding the springs should be released and the springs allowed swinging through 90 degree so that the holes for the nylon plugs are exposed.
Ensuring first that the punch bore is clean, wipe clean the lower punch and then oil the punch head and smear the shank very lightly with the correct grade oil shown on the recommended lubricants chart.
When considering the lubrication of punches it is not always apparent that different circumstance applies to three parts of the punch. These parts are:
‘1’ The crown on top of the head of the punch that is acted upon by the pressure roll and / or ejection cam.
‘2’ The underside of the head that is in contact with the tracks.
‘3’ The ‘shank’ or ‘body’ that slides in the turret guide bores. Traditionally two kinds of oil have been employed for this job. A sticky extreme pressure oil for ‘1’ and ‘2’ and a light machine oil
Traditionally two kinds of oil have been employed for this job. Sticky extreme pressure oil for ‘1’ and ‘2’ and light machine oil for ‘3’.
Insert the punch into the lower punch guide hole through the hole in the Top plate from which the punch-loading plug was removed. The punch must work freely and when pushed through the die, must drop back smartly under its own weight.
Rotate the hand-wheel and fit the other lower punches in the same manner, making sure that after the last lower punch has been fitted, it is lifted up to its highest position and the punch-loading plug then replaced.
The nylon plugs for the punch holding device are supplied with the tool kit and these should now be fitted into the turret, the springs should then be re-positioned over the nylon plug and the round head screw tightened with the screw driver supplied in the tool kit.
IMPORTANT:
After fitting the lower punches and before replacing the feed frame, check that the lower punch tips do not protrude above the die table at the ejection point otherwise the base of the feed frame will be damaged and also the punch tips.
If the punch tips protrude adjust as instructed in paragraphs “Punch Height Adjustment”.
Rotate the turret by means of the hand-wheel as shown arrow direction to ensure that the lower punches have been correctly fitted and pass smoothly through the cam track.
FITTING OF UPPER PUNCHES
Before fitting the upper punches it is necessary to remove take off piece to gain access to the punch guide holes.
Ensure that the upper punch guide holes in the turret are clean.
Clean the upper punches then lubricate the punch head using correct grade of oil and smear punch body very lightly with the correct grade of oil shown on the recommended lubricants chart.
An aid to the application of ENKLO 68 Oil can with a flexible spout. It will pump ENKLO 68 Oil perfectly well and can provide a controlled deposit just where it is needed without mass, and in such a way as the person tooling the machine up finds it easy to keep it off the shanks.
It is also a good idea if one hand is kept totally free of the above lubricants and used solely for handling the shanks. This last point is very important and often neglected.
A further word of caution to clearly mark or identify the ‘punch head oil can’ so that it is not used for general lubrication, and is always to hand and not confused with other cans containing other oils, greases, etc.
The upper punches are loaded into the turret at the parallel section of the upper cam track. Check that each punch is free to move in its guide and capable of dropping under its own weight onto the cam body when lifted up 25 mm. to 40 mm. After fitting all the upper punches, refit take off piece to it position by two screws. Rotate the machine by hand to check that the punches have been correctly lifted and pass freely through the cams.
LUBRICATION OF PUNCHES WHEN THE MACHINE IS IN OPERATION
The upper punch bodies are only lubricated on assembly, because too much oil on the bodies would run down the punch and drop into the product being tabletted, recommended that upper punches be removed, cleaned and re-lubricated when necessary. This should be done at least once a day, preferably at the end of each work shift.
The upper punch heads are lubricated by means of the oil cane with a flexible spout. It will be pump oil perfectly well and can provided a controlled deposit just where it is needed. Upper punch pass downs the upper lowering cam and gets lubricant by upper punch head.
The lower punch bodies are lubricated at the time of punch fitting by recommended oil on the lower cam track apply oil by oil can, by removing turret guards on the left hand side of the machine. Lower punch head are lubricated by Auto lubrication Pump pipe connection fitted on Lower Cam Track Lifting / Lowering during the machine running.
SPECIAL PURPOSE PUNCHES AND DIES
SHAPED PUNCHES AND DIES
Punch and dies, which are any shape other than round, require very careful fitting. The procedure for cleaning the punch guide hole and counterbore is the same as when fitting round punches and dies.
Remove the guide track punch loading piece form the upper cam track.
Thoroughly clean an upper punch and lightly smear the shank with oil, then place it into the upper punch guide hole.
Make sure that it will work up and down freely without any suspicion of thickness in the keyway. With the punch still in position, place a die over the punch tip before entering the die into the counterbore in the die plate. Remove the punch and drive the die into position in the normal manner. Replace the punch and check that it will enter freely into the die for its full depth.
Replace the lightly tighten the die locking screw as a precaution against it standing proud of the periphery of the turret, but no on account use force. If the die should have turned when being driven in, it will be necessary to drive it out and start again. When assured that free fitting is being obtained, fit the lower punch in the usual manner. The remainder of the punches and dies should be fitted with the same care.
When all stations are tooled up the die locking screws must be tightened, and it is then advisable to re-check to ensure that the upper punches enter the dies without ‘tipping’ and that every station is ‘free fitting’.
Special attention should be given to lubrication when using shaped punches and dies, as they do not revolve and disperse the lubricant the same as round punches, this particularly applies to the punch heads and these should be well smeared with oil, care being taken that the underside of the heads are well lubricated. When all the dies are fitted correctly, remove sufficient upper punches to replace the guide track punch- loading piece in the upper cam track, then replace the punches in their respective dies.
1. TAPERED DIES
Dies made with a slight taper in the bore to assist ejection can be supplied when specially ordered. The taper end is etched with a letter “T” on the top face.
Punches and Dies
Punches and dies not kept in good condition can cause various parts of the machine to be worn unnecessarily. The heads of the punches especially require to be carefully examined. If the punch heads are in any way scored or chipped on the end they should be cleaned up immediately, otherwise the peripheral surface of the pressure rolls, ejection cam and weight adjustment will be damaged. This also applies to the underside of the head as any scoring or chipping on this part would damage the lifting and lowering cams and the chamfer on the upper cam.
It must clearly understood, however, that if the overall length of a punch is reduced by clean-up it is absolutely necessary to reduce the length of all the other punches to match i.e. all over punches must match each other for length and all upper punches must match each other for length.
Punch tips, when worn, can be re-faced providing the punch faces are not embossed for hobbed.
Very little can be done with dies when wear takes place in the bore.
Shallow barrelling in the bore by wear at the point of compression can be honed or lapped out but this will make the die bore larger in diameter and allow powder to escape past the lower punch tip, also it will tend to cause a ‘flash’ round the edges of tablets produced.
Tight Punches
Tight punches are responsible for a great dial of really unnecessary wear, both on themselves and many parts of the machine. The most common cause of punches running tight is from the very fine material which is displaced by the upper punch tip when it enters the die bore at the point of compression and, to a lesser extent, from ‘fines’ rising from the movement die table. These fines settle on the exposed portion of the upper punch shanks and contaminate the lubricant, which is then drawn up into the guide holes in the turret.
This trouble of fine powder rising can be overcome to a certain extent, by fitting hard rubber cups to the upper punch tips, but the most positive method of preventing trouble caused by the powder is by the very frequent cleaning of punch shanks and turret guide holes.
Tightening of the lower punches is most commonly caused by an excess extrusion of powder past the lower punch tip and, here again, the recommended procedure is frequent cleaning.
Insufficient lubricant in the powder mix will also cause light punches, but the tightness in this instance will be between the punch tips and the die bores.
