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Position die in the polishing chuck so that the chuck chromium will be removed. Smear diamond paste on felt bob and moisten the extend tooling life. Tum on both units. Do not allow the bob to protrude more than a quar- carry tooling from storage to the press. Also, do not polish the center of the bore bobs and brushes, etc.
The procedures described in this section for cleaning, 9. Remove the die from the chuck, and clean the bore repairing, and polishing punches and dies are part of a with cotton wool.
Following these proce- If unsatisfactory, repeat the oper- dures will help to prolong tooling life and avoid pro- ation. If such problems do occur, the trou- bleshooting tables in Section 6 list corrective actions for the most common tablet and tooling problems. The designer must consid- caused by deficiencies in the granulation, the tablet er the practicality of manufacturing tooling to exact press, or the compaction tooling.
Many times, a defi- specifications, as well as the needs of production, pack- ciency in one component leads to improper functioning aging, and marketing personnel. Advantages of Quality Tooling Tablet Problems Careful consideration and implementation of the many factors involved in a good, workable tooling program The impact of distributing tablets of poor quality is not will reap benefits in many ways.
A well thought-out limited merely to a diminished corporate image. If a design is necessary to produce the highest quality prod- poor-quality tablet provides an improper dosage. The follow- uct can be affected. The importance of producing a ing troubleshooting guide to tablet problems is an high-quality product cannot be overemphasized: the excellent resource for determining the source of and tablet manufacturer's livelihood depends on the compa- correcting the most common problems related to tablet ny's commitment to using high-quality tooling and quality.
TABLE Nonuniform tablet weight 1. Excessive press vibration c. Worn or loose weight-adjustment ramp d. Check dust seals g. Check that antiturning device is set correctly h.
Reduce press speed fl 2. Tail over die missing or not lying flat on die table ii b. Recirculation band leaking c. Excessive vacuum pressure, or nozzle improperly located ii 3. Incorrect setting of hopper spout adjustment b. Granulation bridging in hopper c.
Excessive press speed b. See A3 and AS c. Check speed or shape of feeder paddle a 5. Recirculation scraper missing or bent. Scraper blade bent, worn, or not lying flat; bad spring action. Clean die pocket or check die dimension. Section 5 provides a template for a standard operating Section 6 is the most comprehensive troubleshooting procedures program.
Instructions for setting up a tablet guide to tablet compressing problems available to tablet and tooling directory are supported by forms for obtain- manufacturers. The preventative and corrective measures ing approval of tooling drawings, as well as forms for presented in this section include basic rules for avoiding ordering, inspecting, disbursing, and repairing tooling.
The publisher and the steering committee will continue to track technological advances in the tablet manufacturing industry and identify emerging topics of interest. Readers are also invited to participate in this quest to identify new information needs.
E-mail suggestions can be sent to aphabooks mail. Nonuniform tablet weight 9. Nonuniform tablet thickness 1. See A. Improper setting for overload release b. Pressure rollers not moving freely; punch faces in poor condition d. Air trapped in hydraulic overload system e. Worn pivot pins on roller carriers. Nonuniform tablet density 1. See capping in G. Stratification or separation of granulation in hopper b. Excessive recirculation This causes classification of granulation because only finer mesh material escapes the rotary feeders.
Reduce variations in particle size; reduce machine vibration; reduce machine speed. Add moisture to aid bonding. Excessive vibration of press 1. Inspect drive belt. See A Excessive vibration of press 3.
Press operating near maximum density point of gtanulation. Worn ejection cam b. Add more lubrication to granulation, or taper dies c. Barrel-shaped die bores. Increase pressure to the tooling's limit iiii E. Dirt in product black 1. Clean press more frequently Not pictured b. Excessive or wrong press lubrication c. Use proper punch dust cups and keyway fillers ii d. Rubbing of feeder components e. Punch-to-die binding iii F. Excessive loss of 1. Not pictured a. Feeder base set incorrectly i. Gaps between band's bottom edge and die table b.
Inadequate pressure on hold-down spring. Worn or binding scraper blade b. Outboard scraper edge allowing granulation to escape SI 4. Tail over die not lying flat on table. Compression occurring too high in the die b. Excessive suction or misdirected exhaust nozzle. Excessive clearance between lower punch tip and die bore ii b. Excessive fine particles in the granulation c.
Tapered dies installed upside down. Capping and lamination 1. Compress granulation higher in the die b. Reduce press speed c. Precompress granulation d. Reduce quantity of fine particles in the granulation e. Reduce cup depth on punches f. J:aper dies g. Ensure that punch-to-die clearance is correct. Adjust pressure. Reverse dies b. Hone or lap bores c. Compress granulation higher in the die. Taper dies. Increase quantity of binder; use stronger binder.
Increase level of lubricant. Decrease level of lubricant; blend all ingredients fully before adding lubricant. Use punches with less concave depth.
Refurbish or replace punches. Lower punch set too low at tablet take-off Reworking or refurbishing punches can cause this. Set lower punch tip flush with top of die. Adjust take-off bar. Picking and sticking 1. Check moisture content of granulation b. Check room humidity. Try chrome-plating punch faces. Redesign embossing per TSM guidelines, or consult tooling supplier. Mottled or marked tablets 1. Check oil seals on upper punch guides b. Reduce lubrication of upper punches to an acceptable level c.
Clean and reset components correctly. Re-dry granulation. Reduce particle size. Indistinct breakline or 1. Redesign embossing per TSM guidelines, or consult tooling supplier ii ii 2. Replace punches. Indistinct breakline or 4. Increase binder strength. Compress granulation at a lower pressure. Double impression of 1. Adjust antiturning device b.
Use keyed punches. Chipping or splitting 1. Polish punch tips; replace punches and dies. Poor tooling design e. Splitting of layered tablet 1. Decrease pressure 2. Reduce amount of lubricant. New York: Marcel Dekker, Inc. If the problem cannot be rectified, tion. Often, the problem could easily be avoided by suggestions to prevent recurrence of the problem are using the press correctly.
If left unchecked, the damage given. To help readers isolate the problem, illustrations show- ing the likely damage accompany the description of all Table 20 is a troubleshooting guide to the tooling prob- but two problems. However, to aid clarity, the damage lems most commonly encountered during tablet pro- shown is exaggerated; the actual damage will be far duction. Each problem is described, details of the prob- less pronounced. Excessive hard- None: discard tool; Tools should always The tip has cracked ness for applica- consult tooling be run at the minimum across the face of the tion.
Excessive manufacturer. See cause for 1. See action for 1. A crack will always The tip has cracked follow the line of least and broken away along resistance, which may the angle between the be the sharp angle bevel and tip face. Excessive hard- See action for 1. See comments for 2. The tip has cracked ness. Areas of con- and broken away along centrated stress the angle between a near breakline or breakline and a con- on embossing i.
Excessive pres- sure. See cause for 3. The tip has cracked and broken away along the embossed lettering. Normal die wear Examine dies with mag- If allowed to go too far, This die shows a typi- caused by continu- nifying glass and moni- the die wear can lead cal wear pattern in the ous pressure at the tor tablet ejection..
If a known spread wear, and abrasive granulation is reverse the die when to be compressed, the one end is worn. Check tooling manufacturer that correct steel was can possibly offer a chosen. If wear is a more wear-resistant serious problem, con- material for tooling.
Careful examination of 6 6. Mishandling of Carefully remove dam- this type of damage The edge of the tip has punch punch has age by blending and will reveal clues to its been damaged outside collided with or polishing. Exercise cause. Train beyond its diameter, occurred during fit- personnel to handle the damage most ting of punches to tools properly. In some presses, if 7 7. Contact between Carefully remove dents tools are run or even The punches have met upper and lower by blending and polish- turned without in the press; damage punches in the ing.
Do not run the granulation, the occurred where the press. See comments for 7. See cause for 7. See action for 7. Again, the punches have met in the press, but the opposing punch has no breakline. This type of damage 9 9. Excessive pressure In the early stages can be checked by Pressure has started to first stage for before working length is measuring the tip spread the punch tip; upper and lower affected, punch damage diameter at the working length may not punch.
The blending or polishing. If these spreading will probably Check all punch lengths dimensions vary, occur on both upper before reusing the set; damage has occurred. Rolling the punch. Excessive pressure None: the final stage barrel ori a flat surface Lower punch is over- final stage for of over-pressure can- is a simple way to pressured to the point lower punch. See comments for Excessive pressure See action for Excessive pressure will final stage for have the same effect upper punch.
If not tackled early, 12 Excessive pressure Reduce pressure; this type of damage The head flat has worn and damaged or replace lubricant; repair can lead to serious to the point where frag- worn pressure pressure roller.
Spalling wear and damage to ments of metal are roller. Foreign mat- of the head deposits the tools and the being removed from ter between pres- metal particles in the press. Consult tooling manufacturer. Many tooling problems 13 Tightness of the If possible, polish are caused by Scoring of the punch punch barrel in the punch to restore origi- tightness; marking of barrel is caused by a turret leading to nal condition.
Check the barrel is a definite lack of lubrication possible scoring that guides are clear of indication of trouble. Pay particular becomes punch guides. Poor lubrica- sockets in the turret. Check working length lubricating properties before reworking are destroyed and punch. Ensure that the excessive wear lubrication system is occurs. Press damage is 14 Excessive pres- Check that head flat is possible.
The punch is not rotat- sure. Lack of lubri- not too small to achieve ing, and the pressure cation. Tight punch- satisfactory dwell time roller may be running es or pressure during compression. Check underside of of the head in only one head for damage. If spot. Shaped punches warranted, polish head. Resolve pressure prob- lem; ensure that punch and pressure roller can move freely; ensure adequate lubrication.
A rotating punch is Polish head or increase If the head flat is too The ejection cam is running very tight size of head flat. Ensure small, the compression causing wear on the on ejection, caus- that punches can oper- force is concentrated lower punch head.
Insufficient Resolve ejection prob- ultimately will cause the head flat. Exces- lem; to ease ejection center of the head to sive pressure. Tooling is subjected Damaged, bruised, Always use minimum to continuous high or scored compres- pressure needed to pressure and eventually sion roller. If compression roller is punches are tight, clean and free of burrs unnecessary pressure or bruising. Check cam is applied to tooling, for excessive wear; cams, and compression clean and remove any rollers.
If not corrected, metallic particles from damage to punch the cam track and pres- heads or compression sure rollers. The top of the punch 16 Punch has become None: discard the head may also be Tight punches have tight in the die or punch. Determine damaged. Damage to Incorrect cam moves freely i. Bruised or under its own weight scored press when antiturning device cams. Clean the press to remove metal particles. Ensure that punch guides are clean and correct lubrication is applied.
Check that cam angle is compati- ble with the press cams. Inspect cams for bruises and scores; if needed, repolish or replace cams. This problem is None: discard the This damage is similar similar to 16, but punch. Determine With unenclosed to 16 , but the punch the punch is not cause of problem, and was not allowed to rotating due to the ensure that replace- rotate, resulting in part use of a keyed mentpunchisloose of the head breaking punch or tightening i.
Clean the press to remove metal parti- cles. Excessive tight- ness. Due to wear and refurbishing, head flat has become larger than the neck diameter. When compression force None: discard tool and monitor the condition of tools in use, especially after refurbishing.
Ensure that all metal fragments are removed Severe damage to the press is almost certain. Misalignment of Ensure that internal Burrs are present punch tips in die chamfer of die bores is inside the punch tip bore. Worn punch sufficient. Check for clawing. Eccentricity of concentricity of punch Not pictured punch tips to punch tips.
Ensure that tip-to- body. Extrusion of die bore clearance is product between correct. Increase land or punch tips and die flat on tip edge; ensure bores.
Excessive that land is blended. Compression of an Ensure that the correct The surface finish of abrasive or corro- steel has been chosen. Check for sufficient riorated i. Nottingham, England: I Holland Limited; Further, unless otherwise Head O. Neck: The relieved area between the head and barrel, The first step in learning any industry is mastering its which provides clearance for the cams. With this in mind, the Steering Committee has adopted a list of standard, industry-accepted terms Barrel Shank : The area between the neck and stem; for tablet manufacturing.
An understanding of these the barrel's surface is controlled by the turret punch terms will provide a foundation on which persons new guides to ensure the punch's alignment with the die.
For those who have barrel and neck, which provides a smooth transition industry experience, the information in this section from the barrel to the neck. The cham- fer can reduce wear of punch guides.
Stem: The area of the punch opposite the head, begin- Tooling Terminology ning at the tip and extending to the point where the full diameter of the barrel begins. Tip: The end of the punch that is compatible with the Punch Terminology die bore. The tip determines the size, shape, profile, and identification of the tablet. Head: The end of the punch that guides it through the press's cam track.
Cup: The depression or cavity in the tip. Its depth measurement does not include identification embossing Head Flat Dwell Flat : The flat area of the head that or debossing. Tip Straight: The area of the tip length that extends from the end of the tip to the tip relief. Inside Head Angle: The area of the head that is in contact with the "pull-down" cam lower punches and Tip Length: The straight portion of the stem that is.
Excessive deflec- tions and high impact forces can ultimately lead to dents in the land or a curling in of punch tips. Serious Turret guideways for upper punches are sized suffi- damage to inside head angles can also occur as the ciently larger than the punch barrels to allow free smooth movement of punches thro The resultant clearance also gives rise to an angular end play, which causes the punch tip to be Wear in turret guideways is not uniform throughout the slightly off center relative to the die bore as the punch length of the guideway.
Loads from the cams and com- enters the die. Figure 41 depicts this phenomenon. Die with very little wear occurring in between. Because of bore chamfers ensure that the punch tips are guided into the wear pattern, establishing a specification as to the die without causing damage to the tooling.
As the when a turret is worn cannot be based on measure- turret guideways wear, tip deflection increases and the ments of guideway bore diameters. PUNCH guideway wear. Cover the die pocket in the station that is to be measured with a thin strip of metal. A blank die can also be used. Insert a punch and let it rest on the metal strip or blank die. Set up a surface gauge indicator so that circumfer- ential tip movement can be measured. Tilt the punch back and forth at the head end and measure the T.
Maximum recommended tip deflections may vary according to the press manufacturer, type of tooling i. As a general guideline, a maximum range of. Noticeable punch tip damage and inside head angle wear should also be considered as indications to replace a turret. Holland Limited and Thomas.
Engineering Inc.. TSM-N41 costly work stoppages. On lower punches, the tip Taper: A gradual increase in the size of the die bore length allows vertical movement within the die bore for that extends from the point of compaction to the mouth the metering and compression of granulation, and ejec- of the bore. Tapering of the bore assists in ejecting the tion of the tablet. Barrel-to-Stem Radius: The area at the junction of Die Groove: The groove around the periphery of the the barrel and stem, which provides a smooth transition die, which allows the die to be fixed in the press.
Die Protection Shoulder or Radius: The undercut or Barrel-to-Stem Chamfer: The beveled area located rounded area, respectively, between the die groove and between the barrel and barrel-to-stem radius. The O. Either of these features can be added to prevent chamfer allows the punches to be inserted through tur- damage to die pockets during installation of dies in the ret guide seals. Relief Undercut : The area of increased mechanical Lined Insert Dies: Dies fitted with a liner or insert clearance between the stem and the die bore.
The sharp made from a much harder, more wear-resistant material edge between the tip straight and the undercut area acts such as tungsten carbide or a ceramic see Figure 18, to clean the die. Working Length: The length of the punch from the bottom of the cup to the head flat.
The working lengths General Tooling Terminology of the upper and lower punches control tablet thickness and weight.
Tooling: A collective term that refers to an upper punch, a lower punch, and a die as a unit. For example, Overall Length: The total punch length as measured the term tooling maintenance means the concept per- from the head flat to the end of the tip.
Key: A structure that projects above the barrel's sur- Dwell Time: The length of time the head flat is in con- face and prevents rotational movement of the punches, tact with the main compression roller. During this inter- thus ensuring their alignment to shaped or multi-bored val, the tablet is undergoing full compression. Tolerance: The authorized deviation from a tooling Keying Angle: The relationship of the punch key to dimension measurement.
The deviation allows for prac- the tablet shape. The key's position is influenced by the ticality of manufacture. Die O. The T. Clearance: The difference in size between interacting parts, which creates a working space between the parts and allows for their correct and free movement.
The cavity's shape and size determine the same for the tablet. Abrasion: The premature wear of contact surfaces. Figure 23 on page 48 shows convex to a hard condition. Flat-faced tablets can be fur- Tempering: A process of reheating and cooling steel ther categorized as flat-faced plain, flat-faced bevel- that follows the hardening process.
Tempering toughens edged, and flat-faced radius-edged see Figure 25, page the steel and reduces its hardness. Rockwell Hardness: A measurement of the hardness of steel. The Rockwell C scale is customarily used for Shaped Tablets measuring tool steels. Figure Figure 24 on page 49 uses three common Tablet Manufacturing geometric configurations to illustrate the terminology for shaped tablets.
To produce a tablet with a particular Ii iiiiiil Producing a tablet with a unique design often increases configuration, the tablet shape is reproduced in the tool- a product's recognition among consumers. Although ing used to manufacture the tablets. Before the method tablets can be produced in a variety of shapes and sizes, of reproduction can be discussed, a thorough under- Ii iiil limitations as to their configuration do exist.
The limit- standing of tablet tooling is required. Some categories of tablets are easier to manufacture and com- Modern Tablet Tooling iiiil prise the majority of tablets on store shelves. To achieve this, the die cavity, or bore, is filled with a granulation or powder to The definitions of tablet terminology, which are based a depth that is determined by the position of the lower iiil on the geometric properties of the most common tablet punch.
The lower punch's position determines the iiil. The upper iiil iiiiiill that reason. For the scope of this section, the reader punch tip is then guided into the bore and force is needs only to know that tablets are broadly categorized applied to the punch heads, thereby compressing the as either "rounds" or "shapes. The tablet's shape is determined examples of the tablet categories, figures in section 3 by the configuration of the die bore and the punch tips.
The tablet's thickness and hardness are determined by the amount of compression force applied to the punch heads, whereas its weight is determined by the amount Round Tablets of granulation loaded into the die before compression. Round tablets include primarily convex and flat-faced The basic design of tablet punches and dies used in tablets see Figure 22, page Frequently, industry rotary tablet presses has changed very little since these people use the term concave to describe both the con- presses were first marketed in the late 's.
Only cave surface of a punch cup and the surface of the tablet minor changes, such as refinements to the head and tip produced. Technically, the punch cup is usually a con- radius, tighter tolerances, and higher surface finishes, cavity and therefore produces a tablet with a convex have been made.
In the U. Punches are classified according to their overall length, Dies are classified according to their outside diameters barrel diameter, and the O. These see Figure 2.
This size die can be tool is produced may vary from its specification. The used with B- and B2-type punches. The die is common- allowable variance from a nominal dimension, called its ly referred to as a "BB die. This die is commonly referred to as a "B die. B2-type punches are used predominantly in a The "D" Die, which has an O. During the research stage of a new tablet design, F-type punches and dies not pictured and a single-station laboratory press are used to determine the Comparison of Shaped and Round Tooling approximate amount of compression force and granula- tion needed to produce a tablet with the desired physi- Not surprisingly, punches and dies used to manufacture cal characteristics.
These dimensions are the the desired configuration is reproduced in the punch same for the upper and lower punches. Although the tips and die bores. The [ However, lengths of the upper and lower punches differ. The if a round lower punch is embossed, a key is sometimes upper punch is 5. Again, D-type punch- Rotary Tablet Presses es are often said to have a barrel diameter of 1 inch [ At the fill position, the lower punch is pulled down by die, thus determining the final weight of the tablet.
Increasing the highest vertical position of this cam will The pulling down of the lower punch creates a slight expel more powder, resulting in a lighter tablet; like- vacuum and a void in the die bore. Initially, the com- wise, decreasing the cam's highest vertical position will bined effect of the vacuum and the void allows loose expel less powder, resulting in a heavier tablet. On powder to flow into the die bore. As the die continues manual presses, a manual handwheel controls the posi- its pass under the feed frame, the powder continues to tion of the weight adjustment cam; on automated press- flow into the bore under the force of gravity.
The pow- es, a computer-controlled feedback loop sets the cam's der can be brought over the die by either a gravity feed- position. Pull-Down Position.
Typically, the position of the fill cam remains fixed for Newer press models have a pull-down position, which the entire production run and can only be readjusted or allows the lower punch to be pulled down slightly so changed manually. Keeping the fill cam at a fixed posi- that the top of the powder column in the die bore is tion allows each die to be filled with the same amount below the surface of the die table. Simultaneously, the of powder. After the die bore has been filled, the lower upper punch is lowered by the lowering segment of the punch is transferred to the weight-adjustment cam.
When the upper punch enters the die, precompression begins. The weight-adjustment cam next raises the lower punch, which pushes excess powder out of the filled die. After the die leaves the area of the feed frame, a Precompression Position spring-loaded, knife-edged blade scrapes the surface of the die and removes any excess powder.
During precompression, loose powder is consolidated in the die by the removal of any air trapped in the pow- The highest vertical position reached by the weight- der column and by the physical orientation of the pow- adjustment cam regulates the amount of powder der particles.
Typically, precompression forces tend to expelled and the amount of powder remaining in the be less than the main compression forces. In presses. Qi -,0 WO I IDWG. The "tablet" formed at this step is now ready for main compression. Clearances iiill iii!
The main compression step gives a tablet its final char- to function without making forced contact. This work- acteristics. The final tablet thickness is determined by ing space is called clearance. For example, punch tips iiill the distance between the punch rollers, which deter- must be allowed to enter and leave the die bore without mines the distance between the punch tips.
Again, in making forced contact with the die bore wall. The iiill some presses, the main compression position ,c;. Before reaching the full ejection position, the upper punch is lifted out of the die bore while the lower Producing tooling that match specifications exactly would be accomplished only at great expense to tooling -- iiiiiiil. At the full ejection chase the tooling. For that reason, tolerances, or allow- position, a tablet take-off bar located above the die able deviations, have been established for tooling speci These permissible deviations from specified Making sure that operate properly in the press to produce good-quality tooling and presses conform to TSM specifications can tablets.
Understanding iiiil. The specifications drawings for standard punches and dies Figures diately follows the dimensional value. If the specification is a refer- ence dimension, the abbreviation REF.
An explanation of reference dimensions fol- For dimensions given as a fraction, the appropriate tol- lows the discussions of tolerances and clearances-two erance range is the value labeled as "fractional. Figures 6 and 7 on pages 21 and 22 give detailed illus- The tolerance block also lists the acceptable tolerances trations of the dimensional and configurational differ- for concentricity of die bores, punch tips, and punch ences of angled and domed punch heads.
Angled punch heads. Concentricity refers to the placement of one heads have an outside head angle, whereas domed tooling element in the center of another larger element heads have a radius. Domed heads, which were devel- i.
The oped by European tooling manufacturers, increase the tolerance is given as a T. Indicator readings measure the form or location of one surface with respect to another.
The surface relation- ships of concern here are the die bore to the O. The instrument used to measure concentricity, called a Standardization-Its Purpose comparator, has a readout dial that indicates any devia- and Advantages tions in concentricity as measured by a pointer attached to the dial. Manual was published almost a quarter of a century ago, many U. International press manufacturers are also realizing the economic advantages of making their A reference dimension is derived from, or is the result presses compatible with TSM tooling.
Tablet manufac- of, other toleranced dimensions that are machined first. When making this die, the die groove width inch [6. As shown in Figure 21 fied.
Nonconformance of tooling to will perform well with standard TSM tooling. The remaining sections of this manual provide the nec- essary information to determine whether a new tool conforms to TSM specifications.
The reader will also find detailed guidelines on tablet design, standard oper- ating procedures for procuring and inspecting tooling, and step-by-step instructions for maintaining tools-an important function in protecting tooling and presses. It is considered tions. Although the nominal dimensions shown on these auxiliary information and does not govern drawings have remained basically unchanged over the production or inspection operations.
A reference years, the tolerances for these dimensions and, surface dimension is a repeat of a dimension or is derived finishes of the tooling have changed, to some degree, as from other values shown on the drawing or on the equipment used to manufacture the tooling has related drawings. In some cases, the tolerances are based strict- ly on what is reasonably achievable using the existing The O. In most cases, however, the tolerances are toleranced dimensions except for flat-faced tip the result of careful consideration of what limits pro- configurations : the W.
Effect of Tooling Dimensions The major concern with cup depth and W. Variations in the W. The effect of the tolerance range for working ing. In presses that compress tablets to a constant thickness, variations in W. Electronic weight-monitoring devices Working Length force and thickness types are affected by punch length; the effect is more pronounced when the device is used to reject individual tablets of nonuniform weight than when used for actual weight control.
Cup depth, overall length 0. If the variation in a reference dimension and therefore does not have a length throughout the set is within the tolerance range, specified tolerance.
Ii iii. If embossing or a bisect is present, the Head Flat Diameter indicator tip is positioned between the embossing. The common practice of reworking head flats on The diameter of the punch head flat and the turret speed of the press determine the amount of time the tablet material undergoes maximum compression.
The time of punches throughout the useful life of a set of tooling maximum compression, often referred to as can result in working lengths that vary considerably dwell time, directly affects the tablet hardness. Aside from having to change the height of the tablet ejection cam, a decrease The TSM specifications for the head flats of B- and D- in W.
These dimen- tolerance range. The specifica- and preferably for consistency within the given tion is based on the "preblended" dimension, rather tolerance-not for a number obtained by subtracting than the actual finished dimension, because of the diffi- the cup depth from the O. A set of punches should be culty in measuring exactly where the blend radius ends separated into uppers and lowers and inspected for and the head flat starts.
These preblended dimensions variances in the W. For example, all are often designated as "over sharp comers OSC. As long as both upper and For B-type punches, the head flat is approximately. Similarly, for a D-type punch, consistent. The cup depth should also be inspected as a single Tip Straight dimension.
This relieved area at Head Thickness the tip of the punch guides the punch in the die, and provides a tight fit between the punch and die to prevent On many tablet presses, the thickness of lower punch the loss of fine granulation particles from the die bore. The undercut, or relief, forms a sharp ance range. Punch heads, particularly the inside head comer at the back edge of the tip straight; this comer angles, are the most commonly reworked area on tablet can scrape film off the die wall as the lower punch tooling.
When punch heads are reworked, maintaining a moves up and down in the die. An undercut can also be uniform punch head thickness throughout the set should added to upper punches to improve retention of dust be the primary concern. Several A few tooling specifications were revised to accommo- new press models were added to these tables; a few dis- date variability in tooling dimensions among tablet continued models were deleted.
Some corrections to presses. Further, new press models and their tooling tooling dimensions for existing presses were also made. Punch Tip Compression Forces.
The fourth edition provided methods for determining the punch tip Among presses currently available, the barrel diameter force ratings for concave tooling. This new edition pro- of B2-type lower punches can range from. Rather than give a range for the specifi- F. See pages in section 4. Read- cation,. This change is noted on value of. Figures 2 see page 6 and 21 see page Readers can also check Table 9 on page 42 to see whether their press model is listed.
This table lists tooling specifica- tions for special rotary presses. Tooling Design Options Tablet presses introduced during the s run at high- Maximum Tablet Size for Round Tablets er speeds, are more automated, and are more precise. Ii iiil Most press manufacturers ensured these presses were iii In the fourth edition, the maximum tablet size for round compatible with standard tooling.
For certain tableted iii. European tooling manufac- products, though, the use of standard tooling on some iii iii turers still consider this specification correct for Euro- presses makes it difficult to maintain the speeds and pean tablet presses. However, some members of the accuracy the presses were engineered to achieve.
Table 2 ever, tooling options must be distinguished from tooling page 34 lists both values but notes that, when 1 [25] requirements. Some tooling features might be consid- tablets are manufactured, a special tool may be required ered optional for certain presses but required for others. The press manufacturer must supply specifications for Iii iii tooling options needed to obtain peak performance from a press. The following tooling options can benefit Ii ii.
Available Key Space both high-speed and standard presses. Tablet press manufacturers were asked to review Tables I ii 4 and 5 page 38 as part of the updating of the manual.
This change reduced the available key space with presses fitted with rubber or plastic guide seals. I See Figure 1, Punches with optional mirror-finished heads are espe- page 3.
The absence of a chamfer on the tip end of the punch These metals eliminate premature head wear and pro- barrel-to-stem chamfer can make installing punches long tool life, but they can also contaminate lubrication, difficult. If a punch is forced past the seal, the seal can turning it to a black, dark green color. The typical finish of a punch head is done with of the granulation. Damaged lower guide seals can fine emery or fine abrasive pads. This finish leaves fine allow granulation to seep into the lower-punch guides radial lines on the contact surfaces of the heads, which and mix with the lubrication, causing tight punches and have a filing effect on the softer cams, causing discol- possibly press seizure.
Using a soft cotton wheel and fine polishing compound to polish the punch heads to a mirror finish helps to Domed Punch Heads keep the lubrication cleaner and prolongs cam life. Domed A short upper-punch tip straight is a tooling option pri- punch heads have the same top head radius and head marily for tablet presses with lubrication seals. In some flat as that of the Eurostandard head. Figures 6 and 7 presses, the lower section of the upper-punch guides see pages 21 and 22 show the differences between the and the upper section of the lower-punch guides are fit- TSM, TSM and Japan Norm domed, and the European ted with these seals.
The seals serve to keep the lubrica- head configurations. However, the Norm domed head are the same as those for the TSM punch seals are effective only if they maintain a seal domed head.
If the upper-punch tip is too long, it can be pulled up past the Pitting of the head referred to technically as "surface- seal, allowing seepage of lubrication.
This seepage can origin fatigue" is identified by voids in the head flat. I Table 4 see page 38 shows TSM standard head style. The failure is caused primari- the most common presses fitted with upper-guide seals ly by the application of extreme compression forces, and their punch tip length requirements.
The impact of heavy forces at high speeds has a work-hardening effect, contributing Key Types and Positions to the pitting of the head flat. This form of pitting is detrimental to the life of the punches and pressure Fitting optional keys to shaped punches, and in some rollers.
Rotation of shaped punches can result in misalignment The area of concern is the inch [7. Such rotation on a round punch can This radius is required for the standard American punch cause double debossed images and misplacement of head. The domed head reduces the stress placed on bisects or debossing. I press is ordered. Existing presses would require modifi- cation to accept keyed lower punches.
Illustrations and Tables. All rights reserved Printed in the United States of America Notice of Copyright: No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any mean-electronic, mechanical, photocopying, recording, or otherwise- without written permission from the publisher with the exception of certain forms on which permission to copy is stated thereon.
Notice of Liability: The publisher and the Tableting Specification Steering Committee have made every effort to ensure the accuracy and completeness of the information in this publication. However, the publisher, steering committee members, edi- tors, contributors, and reviewers cannot be held responsible for the continued currency of the information, any inadvertent errors or omissions, or the application of this information. Therefore, the named parties shall have no liability to any person or entity with regard to claims, loss, or damage caused or alleged to be caused, directly or indirectly, by the use of information contained herein.
Tableting specification manual : previously referred to as the IPT standard specifications for tableting tools. ISBN paperbound : spiral 1.
Tablets Medicine -Standards-United States. Tableting-Standards-United States. American Pharmaceutical Association. Tableting Specification Steering Committee. Equipment and Supplies-standards. Technology, Pharmaceutical-instrumentation. QV 26Tl13 ] RS T2 A46 '. Linda L. Two key configurations are available: the standard punch rotates. Flutes are recommended for extreme Woodruff key, sometimes referred to as the pressed-in cases such as punches that hang up or stick in the guide- key, and the fixed parallel or flat key, often referred to ways.
Punches that show extreme premature wear or as the European key see Figure 20, page In these instances, effectiveness Hi-Pro. The latter has a tab on each side of the exposed of the guide seals is lost, causing shifting of granulation top section and rests on the barrel to keep it secure by and seepage of lubrication.
When barrel flutes are used eliminating the rocking action common to the standard on presses with punch retainers, the lower punch retain- Woodruff key.
To obtain maximum security for high- ers should be removed for tound tooling because of the speed presses, the Woodruff key should be fastened into punch rotation.
For shaped tooling, the radial location the barrel using screws. I of the flutes is critical; the flutes should be positioned so as not to interfere with the retainers. The fixed parallel key is a longer flat key, either 1 [ I Dies are usually manufactured from D-3 steel. Although The axial and radial position of a key is critical to this steel grade does not provide toughness, it is superi- obtain maximum press performance.
Unfortunately no or for wear. Dies are not subjected to the same pressures standard has been established for upper guide key slots or shock as the punches, and therefore can be manufac- due to the particular requirements of the many styles of tured from a larger selection of materials.
Table 4 also shows the most common presses with upper punch seals and their key axial posi- The most common die used in compression of abrasive tion. If a key is placed too low or extends too long on or corrosive formulations is the carbide-lined die. Although car- resulting in product contamination. If the key is placed bide dies cost more, they offer the advantages of superi- too high on the barrel, it can travel out of the key slot at or die wear and tablet quality; die life is also easily the top of the punch guide, possibly causing severe increased by 10 times in most cases.
If the radial position loading. This is also true for the steel sleeve. The grooves serve to reduce the amount of bearing Ceramic-lined dies are becoming more widely used as surface to help eliminate friction, thereby allowing the tougher grades become available. The most common punch to move easier in the guideway. On a punch with ceramic grade used in compression dies is currently a round tip configuration, the grooves can also help PSZ partially stabilized zirconia.
Dies lined with PSZ scrape granulation form the punch guide as the lower have the same general wear characteristics and require.
The press designs, these presses will provide maximum ceramic liner, which is commonly a light cream or tablet output and trouble-free operation while using white color, is quickly gaining popularity over carbide. Swarbrick J, Boylan JC, eds.
Volume 15 of countries, and other countries to make their newer press Encyclopedia of Pharmaceutical Technology. Some of the newer international press- Amiss J, ed.
Machinery's Handbook New York: maximum efficiency rate achieved in U. Fig- Industrial Press; Die Figures Figure 14 Standard. List of Tables vi Acknowledgments
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