tablet press operation - Techceuticals

1 WReprinted From tablets & Capsules, October occurs when granules attach themselves to the faces oftablet press punches. Picking is a more specific term thatdescribes product sticking only within the letters, logos, ordesigns on the punch faces. This article explains the causes ofsticking and picking and describes the steps you can take toresolve both a product begins sticking to the punch face, theblame game starts. Unchecked, the finger-pointing canzoom around to encompass every person with a hand inthe tablet -making process. No one wants to bear theresponsibility for the your colleagues in R&D you hear, It didn t stickto the punches in our single-station lab press . Check withthe tablet press operators.

2 They re not running the tabletpress correctly. When you check with the tablet pressoperators, they say it s a granulation problem. If theproduct had been granulated correctly we wouldn t havesticking problems. The people in quality assurance pointout that the product is sticking to the tooling. They sug-gest that you look for worn tooling or tooling that needsto be polished. Or maybe the tools weren t made cor-rectly to start with. Call the tooling vendor, they so it the problem coming from the tablet press or theproduct formula? Is it the tooling or is it the granulatingand drying process? Is it the operators? No one knows and pickingSticking is one of the most common problems oftablet making.

3 It occurs when granules attach and stick tothe faces of the punches instead of locking together tocreate a uniform tablet . The photos above show examplesof tablets rejected because of sticking . Figure 1 shows theface of an upper punch with sticking product. Picking is aspecific type of sticking in which particles stick withinthe letters and logos that are embossed or debossed onthe faces of the compression tooling. See Figure whether it s sticking or picking, the result isa defective tablet . To salvage the batch, you may have tovisually inspect the tablets . This certainly will slow pro-duction and decrease yields, but there is no formulation is completed; you can t send it backdown the hallway for can happen at any time throughout a batch.

4 Itoccurs most often at the initial setup of the tablet press ,but it might just as easily appear randomly in a productionrun. It might also appear at regular, predictable press operationSticking and picking: Some causes and remediesMichael D. TouseyDI Pharma Techd-Tousey art-10-15 12/1/04 11:31 AM Page 1 With some prod-ucts, sticking is sopredictable thatoperators considerit a success whenthey can run for 2hours without themoisture content,particle size distri-bution, and otherproduct properties will help you predict whether a prod-uct will compress without sticking . However, even prod-ucts that meet your specifications may stick and fact is, you may not know how well a product willcompress until it is on the tablet press .

5 This article will offer some strategies to identify thecauses of and solutions to sticking and picking. Thesource of the problem may relate to the product, the tool-ing, the upstream processes, or the operation of the tabletpress. It might also be a combination of these granules make good a tablet press is set up for the first productionrun, the operator will first adjust the weight cams to getthe correct tablet weights. (Actually, you adjust the posi-tion of the lower punch in the die. In doing so, you con-trol the volume of the die cavity. At a given bulk density,the die volume will correspond directly to tablet weight.)Once you have the weights right, you adjust to attainthe proper tablet thickness.

6 tablet hardness is determinedby a combination of variables, including tablet weight, tablet thickness, press speed, and the dwell time of theupper punch in the die at full compression with granules that are super-sensitive to com-pression call them sticky granules can form excellenttablets. But they are also prone to sticking to the punchfaces. If this is the problem on your press , you are likelyto see the problem worsen over the course of the produc-tion run. That s because granules super-sensitive to com-pression will readily compact as they flow through thehopper and into the feed a powder compacts before it reaches the die cavity,the bulk density of the formulation increases, impedingyour ability to control the tablet weights.

7 As the weightof the tablets fluctuates, so does the compressive variation in force, in turn, can exacerbate the prod-uct s tendency to stick. That starts a downward trend, andthat s why the sticking gets worse and tablet press operators know a trick aboutcompression: If sticking is a problem, they quickly over-compress the product and make very hard tablets for a fewpress revolutions. This quick action, known as shockingthe press can work very well. Why? The answer is fairlysimple: The stronger compaction forces cause the granulesto bind with the tablet and pull the stuck granules awayfrom the punch face. But be careful when using this methodto shock the press .

8 If you overload the punches, you willdamage them or even break operators can also save a sticking batchwhen inexperienced operators don t know where to operators, for example, often hear changesin the sound of the press and know that the product issticking. Their first action might be to change the com-pression settings, such as by increasing the force, reduc-ing tablet thickness, or decreasing pre-compression thick-ness. They may even slow the press . A good operatoralways pays attention to the tablet and the tablet sooner you identify a sticking problem, the fasteryou can resolve p s and q s of toolingSticking and picking are usually the result of many fac-tors, but because they happen on the face of the punch,it s easy to blame the tooling.

9 And sometimes the blame isplaced there correctly, especially in the case of occurs on the letters, logos, and other designsof the punch face. Usually you ll find the picking withinthe closed numbers and letters that form islands. These numbers are 0, 4, 6, 8, and 9. Some of the lettersare A, a, B, b, D, d, e, P, p, Q, q, and so on. See Figure manufacturers know about these problematicnumbers and letters and do a good job of making punchfaces that prevent picking. You can even order toolingwith a pre-pick feature. A pre-pick feature means thatthe punch face has islands that are not as deep as the restof the embossing. Despite the shallower islands, thepunch still makes a clean, legible indentation.

10 Anotherstrategy is to change the height and angle of the emboss-ing. Doing so produces a tablet with the same appearancebut without the picking that tablets destined to receive a coating will havelettering that is less severely angled, wider, and shallowerthan the lettering on non-coated tablets . Thus the designof coated tablets helps reduce sticking and choice of steel and the degree of polish on thepunch will also affect picking. Type D2 and Type 440 Csteel contain more chromium than other steels, whichFigure 1 Product sticking to the face of an upper punchFigure 2An example of pickingTabletLower punchThe islands formedby closed lettersand numbers areprone to art-10-15 12/1/04 11:31 AM Page 2reduces sticking and picking.