145:
Due to the nature of oxygen entrapment in epoxy during the pouring and curing period it is common to have distortions and cavitation in the final injection mold. Pressurizing the epoxy during the curing period is a form of surface quality retention. External pressures can be created with the use of a
128:
like 7050 and 7075 are preferred for the best mechanical properties in aluminum, they are comparable to low to mid carbon steel molds. Copper alloys, like pewter, or bismuth alloy molds can be cast around a model to create strong molds with higher molding temperatures than epoxy molds. The casting
104:
Benchtop injectors are smaller and simpler than their larger industrious counterparts because they rely on the operator to manually inject melted polymer into the mold and remove the finished part from the mold. Production injectors automatically inject melted polymer at a prescribed rate into the
123:
Low cost benchtop CNC milling machines allow home enthusiasts to machine molds out of softer metals. Rather than P20 tool steel, most grades of aluminum can be machined into working molds capable of 1000 plus cycles. Mic 6 cast aluminum is more stable post machining and during cycles than hot
109:
in the part where the two halves meet, and the nozzle of the injector must be pressed tightly against the inlet port of the mold to prevent the escape of melted polymer and a defect in the finished part. In a benchtop injector this is done manually by clamping or bolting the mold together and
35:
In hobby injectors injection pressure is generated manually by the operator, with a lever or gear translating the operator's effort to the required pressure. The most common hobby injection machine uses a handle to press down with. This enables the user to generate roughly 250 pounds-force
64:
Hobby injection molding has a variety of applications including the creation of low cost prototypes, new inventions, replication of lost or broken parts, and provides homeowners the opportunity to build anything. Hobby injection molding is a low cost method of repeatable production.
150:
to crush air trapped inside the epoxy mold during curing. As time passes over a 24-hour period the oxygen bubbles will not be able to escape and will cure directly inside the mold. With sufficient pressure these small cavities will be invisible to the naked eye.
141:
with a metal powder (generally aluminum) to form a mold. Atomized aluminum allows for the distribution of heat from the mold surface outward toward the edges. This typically preserves the surface quality for 50-100 cycles on a single epoxy mold.
110:
clamping the complete mold into the injector. In a production injector this is accomplished with hydraulic or pneumatic actuators, which increase the cost of the machine but dramatically reduce the labor required to produce a finished part.
105:
mold, cool the mold to rapidly solidify the polymer, then eject the part from the mold once it's cool. The two halves of the mold must be pressed together with great force to prevent a
170:
Single use injection molds can be achieved through the use of plaster of Paris. The mold breaks down after the first shot and will rarely allow for the injection of a second shot.
158:
and will require a pressure of 100 kPa (29 inHg) in order to create near vacuum conditions. This can be achieved with the use of a 2-stage
285:
221:
248:
129:
around a model to create each mold part produces complex molds quickly. The parts can also capture detailed surface finishes.
52:
milling machines, producing a metal mold was prohibitively expensive for most hobbyists. With a small CNC mill and personal
405:
81:
77:
48:
It is not known when the first hobby injection molder was constructed. Before the development of inexpensive
106:
53:
37:
380:
28:, hold molds on a smaller scale. Benchtop injectors have become more common as inexpensive CNC
184:
179:
124:
extruded grades like 6061 and is easy to machine however it has worse mechanical properties.
125:
29:
289:
225:
155:
147:
399:
85:
73:
311:
204:
159:
93:
89:
270:
96:) have all been used successfully with lever-actuated benchtop injectors.
360:
154:
Degassing the epoxy during the curing period can also be done using a
56:
tools, though, even complex shapes can be cut easily and accurately.
138:
49:
32:
have reduced the cost of producing molds in a home workshop.
16:
Small scale, individual use of injection molding technology
286:"Plastic Injection Molding Attachment for the Drill Press"
313:
What Can You Do with an
Injection Molding Machine,pg 186
206:
What Can You Do with an
Injection Molding Machine,pg 184
249:"Home Plastic Injection Molding Offered on Kickstarter"
345:
Secret of building a plastic injection molding machine
36:(1.1 kN) of downward force, through the use of
381:"Injection Molding Basics for the Minimal Mold"
361:"Injection molding & plastic prototyping"
8:
288:. David J Gingery Publishing. Archived from
224:. David J Gingery Publishing. Archived from
271:"Hand-operated injection molding machine"
273:. Us Pat. #4,235,584. November 25, 1980.
326:
196:
7:
379:Maxon, Kenneth (February 13, 1997).
316:. Popular Mechanics. September 1970.
209:. Popular Mechanics. September 1970.
222:"Plastic Injection Molding Machine"
162:that is capable of 2 Pa (15 μmHg).
14:
185:Computer numerical control (CNC)
1:
359:Lancaster, Don (March 1996).
146:pressure pot connected to an
366:. Nuts & Volts Magazine
422:
383:. Seattle Robotics Society
137:Epoxy molds typically mix
343:Gingery, Vincent (1996),
24:machines, also known as
22:Hobby injection molding
228:on February 9, 2010
26:benchtop injectors
406:Injection molding
180:Injection molding
413:
392:
390:
388:
375:
373:
371:
365:
348:
330:
324:
318:
317:
308:
302:
301:
299:
297:
292:on March 8, 2010
284:Gingery, Vince.
281:
275:
274:
267:
261:
260:
258:
256:
251:. rapidreadytech
244:
238:
237:
235:
233:
220:Gingery, Vince.
217:
211:
210:
201:
166:Single use molds
30:milling machines
421:
420:
416:
415:
414:
412:
411:
410:
396:
395:
386:
384:
378:
369:
367:
363:
358:
355:
342:
339:
334:
333:
325:
321:
310:
309:
305:
295:
293:
283:
282:
278:
269:
268:
264:
254:
252:
246:
245:
241:
231:
229:
219:
218:
214:
203:
202:
198:
193:
176:
168:
135:
121:
116:
102:
71:
62:
46:
17:
12:
11:
5:
419:
417:
409:
408:
398:
397:
394:
393:
376:
354:
353:External links
351:
350:
349:
338:
335:
332:
331:
319:
303:
276:
262:
247:Newman, John.
239:
212:
195:
194:
192:
189:
188:
187:
182:
175:
172:
167:
164:
156:vacuum chamber
148:air compressor
134:
131:
120:
117:
115:
112:
101:
98:
70:
67:
61:
58:
45:
42:
15:
13:
10:
9:
6:
4:
3:
2:
418:
407:
404:
403:
401:
382:
377:
362:
357:
356:
352:
346:
341:
340:
336:
328:
323:
320:
315:
314:
307:
304:
291:
287:
280:
277:
272:
266:
263:
250:
243:
240:
227:
223:
216:
213:
208:
207:
200:
197:
190:
186:
183:
181:
178:
177:
173:
171:
165:
163:
161:
157:
152:
149:
143:
140:
132:
130:
127:
118:
113:
111:
108:
99:
97:
95:
91:
87:
86:polypropylene
83:
79:
75:
68:
66:
59:
57:
55:
51:
43:
41:
39:
33:
31:
27:
23:
19:
385:. Retrieved
368:. Retrieved
344:
337:Bibliography
327:Gingery 1996
322:
312:
306:
294:. Retrieved
290:the original
279:
265:
253:. Retrieved
242:
230:. Retrieved
226:the original
215:
205:
199:
169:
153:
144:
136:
122:
103:
74:Polyethylene
72:
63:
60:Applications
47:
34:
25:
21:
20:
18:
387:October 24,
370:October 25,
296:October 24,
232:October 24,
160:vacuum pump
133:Epoxy Molds
126:7000 series
119:Metal molds
92:(including
90:polystyrene
191:References
100:Equipment
69:Materials
400:Category
255:June 10,
174:See also
38:leverage
44:History
88:, and
76:(both
364:(PDF)
347:, DGE
139:epoxy
114:Molds
107:flash
389:2009
372:2009
298:2009
257:2013
234:2009
94:HIPS
82:HDPE
80:and
78:LDPE
84:),
54:CAD
50:CNC
402::
40:.
391:.
374:.
329:.
300:.
259:.
236:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.