Cakɛda minnu bɛ ɲɔgɔn cɛ
PLW walima Made ka kɛɲɛ ni komandi ye
Nɛgɛ min bɛ wele ko Carbon Steel
Plastique Sac+Carton Box+Plywood Case
PLW walima Made ka kɛɲɛ ni komandi ye
Sariya
| A sɔrɔli: | |
|---|---|
| Hakɛ: . | |
KC Series Duplex Roller Chain, min bɛ wele tuma caman na ko coupling chain, o bɛ kɛ roller chain coupling assemblies ka transmission yɔrɔ koloma ye. A dabɔra kun na walasa ka fanga cicogo sɛgɛsɛgɛlen sɔrɔ jirisunba ni jiribolo la izini bolifɛnw kɔnɔ. Ni a ni ɲɔgɔn cɛ ni ɲɔgɔndan sɔgɔlan fila ye minnu bɛ bɛn ɲɔgɔn ma, minnu sigilen don u danma bolifɛnw ni bolifɛnw kan, o cakɛda duplex roller cakɛda in bɛ baara kɛ ni pikirijikɛlan fila bɛɛ ye walasa ka girinya wuli ka ɲɛ. A ni couplings rigides minnu bɛ a ɲini ka shaft alignment ultra-precise de wajibiya, o cakɛda-based solution bɛ controlled flexibilité don transmission system kɔnɔ. O ye fɛɛrɛ ye min musaka ka dɔgɔ, farati man bon masinw na, yɔrɔ minnu na, jirisunw labɛnni dafalen tɛ se ka mara kudayi, wa ɲɔgɔndan misɛnninw tɛ se ka bali. An ka portfolio dafalen bɛ KC duplex cakɛda jɔnjɔnw, AF seriyali ani BF seriyali cakɛda kɛrɛnkɛrɛnnenw kan minnu ka bon kosɛbɛ, ni u bonya ka ca walasa ka girinya hakɛ danfaralenw wasa, sigili yɔrɔ gɛlɛyaw ani baarakɛyɔrɔ wajibiyalenw.
Cakɛda No. |
Pitch P (mm) . |
Diamètre de rouleau d1 max (mm) Bamako, Mali. |
Kɔnɔna tabali ni ɲɔgɔn cɛ bonya b1 min (mm) . |
Diamètre de broche d2 max (mm) Bamako, Mali. |
Pin janya L max (mm) . |
Pin janya Lc max (mm) . |
Kɔnɔna plati juguman h2 max (mm) . |
Plaque ka bonya T max (mm) . |
Kɛrɛnkɛrɛnnenya la, Pt (mm) . |
Tensile fanga min (kN/lbf) . |
A ka girinya hakɛ dantɛmɛnen Qo (kN) . |
Kisɛ kelen girinya q (kg/pc) . |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
4012 |
12.700 |
7.95 |
7.85 |
3.96 |
31.0 |
32.2 |
12.00 |
1.50 |
14.38 |
28,2/6409 kɔnɔ |
35.9 |
0.20 |
4014 |
12.700 |
7.95 |
7.85 |
3.96 |
31.0 |
32.2 |
12.00 |
1.50 |
14.38 |
28,2/6409 kɔnɔ |
35.9 |
0.23 |
4016 |
12.700 |
7.95 |
7.85 |
3.96 |
31.0 |
32.2 |
12.00 |
1.50 |
14.38 |
28,2/6409 kɔnɔ |
35.9 |
0.26 |
5014 |
15.875 |
10.16 |
9.40 |
5.08 |
38.9 |
40.4 |
15.09 |
2.03 |
18.11 |
44,4/10091 kɔnɔ |
58.1 |
0.49 |
5016 |
15.875 |
10.16 |
9.40 |
5.08 |
38.9 |
40.4 |
15.09 |
2.03 |
18.11 |
44,4/10091 kɔnɔ |
58.1 |
0.56 |
5018 |
15.875 |
10.16 |
9.40 |
5.08 |
38.9 |
40.4 |
15.09 |
2.03 |
18.11 |
44,4/10091 kɔnɔ |
58.1 |
0.63 |
6018 |
19.050 |
11.91 |
12.57 |
5.94 |
48.8 |
50.5 |
18.00 |
2.42 |
22.78 |
63,6/14455 kɔnɔ |
82.1 |
1.06 |
6020 |
19.050 |
11.91 |
12.57 |
5.94 |
48.8 |
50.5 |
18.00 |
2.42 |
22.78 |
63,6/14455 kɔnɔ |
82.1 |
1.18 |
6022 |
19.050 |
11.91 |
12.57 |
5.94 |
48.8 |
50.5 |
18.00 |
2.42 |
22.78 |
63,6/14455 kɔnɔ |
82.1 |
1.30 |
8018 |
25.400 |
15.88 |
15.75 |
7.92 |
62.7 |
64.3 |
24.00 |
3.25 |
29.29 |
113,4/25773 ye |
141.8 |
2.38 |
8020 |
25.400 |
15.88 |
15.75 |
7.92 |
62.7 |
64.3 |
24.00 |
3.25 |
29.29 |
113,4/25773 ye |
141.8 |
2.65 |
8022 |
25.400 |
15.88 |
15.75 |
7.92 |
62.7 |
64.3 |
24.00 |
3.25 |
29.29 |
113,4/25773 ye |
141.8 |
2.91 |
10018 |
31.750 |
19.05 |
18.90 |
9.53 |
76.4 |
80.5 |
30.00 |
4.00 |
35.76 |
177,0/40227 ye |
219.4 |
4.51 |
10022 |
31.750 |
19.05 |
18.90 |
9.53 |
76.4 |
80.5 |
30.00 |
4.00 |
35.76 |
177,0/40227 ye |
219.4 |
5.51 |
12018 |
38.100 |
22.23 |
25.22 |
11.10 |
95.8 |
99.7 |
35.70 |
4.80 |
45.44 |
254,0/57727 ye |
314.9 |
8.14 |
12022 |
38.100 |
22.23 |
25.22 |
11.10 |
95.8 |
99.7 |
35.70 |
4.80 |
45.44 |
254,0/57727 ye |
314.9 |
9.95 |
Cakɛda No. |
Pitch P (mm) . |
Diamètre de rouleau d1 max (mm) Bamako, Mali. |
Kɔnɔna tabali ni ɲɔgɔn cɛ bonya b1 min (mm) . |
Diamètre de broche d2 max (mm) Bamako, Mali. |
Pin janya L max (mm) . |
Pin janya Lc max (mm) . |
Kɔnɔna plati juguman h2 max (mm) . |
Plaque ka bonya T max (mm) . |
Tensile fanga min (kN/lbf) . |
A ka girinya hakɛ dantɛmɛnen Qo (kN) . |
A girinya mɛtɛrɛ kelen q (kg/m) . |
|---|---|---|---|---|---|---|---|---|---|---|---|
08AF36 ye |
12.700 |
7.95 |
21.70 |
3.96 |
30.8 |
32.1 |
12.00 |
1.50 |
13,8/3135 kɔnɔ |
16.20 |
1.070 |
10AF13 ye |
15.875 |
10.16 |
16.31 |
5.08 |
27.6 |
29.1 |
15.09 |
2.03 |
22,2/5045 kɔnɔ |
27.50 |
1.350 |
10AF71 ye |
15.875 |
10.16 |
19.00 |
5.08 |
30.5 |
32.2 |
15.09 |
2.03 |
21,8/4901 kɔnɔ |
24.40 |
1.480 |
*10AF75 ye |
15.875 |
10.16 |
45.60 |
5.08 |
57.0 |
58.5 |
15.09 |
2.03 |
21,8/4901 kɔnɔ |
24.40 |
2.540 |
12AF2 ye |
19.050 |
11.91 |
19.10 |
5.94 |
32.6 |
34.4 |
18.00 |
2.42 |
31,8/7227 ye |
38.20 |
1.900 |
12AF6 |
19.050 |
11.91 |
18.80 |
5.94 |
31.9 |
33.5 |
18.00 |
2.42 |
31,8/7227 ye |
38.20 |
1.870 |
12AF26 |
19.050 |
11.91 |
19.36 |
5.94 |
31.9 |
33.5 |
18.00 |
2.42 |
31,8/7227 ye |
38.20 |
1.940 |
12AF34 ye |
19.050 |
11.91 |
19.00 |
5.94 |
31.9 |
31.9 |
18.00 |
2.42 |
31,1/7066 ye |
38.20 |
1.860 |
12AF54 ye |
19.050 |
11.91 |
19.50 |
5.84 |
31.9 |
31.9 |
18.00 |
2.29 |
31,1/7066 ye |
38.20 |
1.607 |
*12AF97 ye |
19.050 |
11.91 |
35.35 |
5.94 |
48.8 |
50.5 |
18.00 |
2.42 |
31,8/7149 ye |
38.20 |
2.630 |
*12AF101 ye |
19.050 |
11.91 |
37.64 |
5.94 |
51.2 |
52.9 |
18.00 |
2.42 |
31,8/7149 ye |
38.20 |
1.990 |
*12AF124 ye |
19.050 |
11.91 |
20.57 |
5.94 |
33.9 |
35.7 |
18.00 |
2.42 |
31,8/7149 ye |
38.20 |
1.910 |
16AF25 |
25.400 |
15.88 |
25.58 |
7.92 |
42.4 |
43.9 |
24.00 |
3.25 |
56,7/12886 kɔnɔ |
63.50 |
3.260 |
*16AF40 ye |
25.400 |
15.88 |
70.00 |
7.92 |
87.6 |
91.1 |
24.00 |
3.25 |
56,7/12886 kɔnɔ |
63.50 |
5.780 |
*16AF46 ye |
25.400 |
15.88 |
36.00 |
7.92 |
53.3 |
56.8 |
24.00 |
3.25 |
56,7/12886 kɔnɔ |
63.50 |
3.880 |
*16AF75 ye |
25.400 |
15.88 |
56.00 |
7.92 |
73.5 |
76.9 |
24.00 |
3.25 |
56,7/12746 kɔnɔ |
63.50 |
5.110 |
*16AF111 ye |
25.400 |
15.88 |
45.00 |
7.92 |
62.7 |
65.8 |
24.00 |
3.25 |
56,7/12746 kɔnɔ |
63.50 |
4.480 |
*16AF121 ye |
25.400 |
15.88 |
73.50 |
7.92 |
91.3 |
94.7 |
24.00 |
3.25 |
56,7/12746 kɔnɔ |
63.50 |
6.000 |
Cakɛda No. |
Pitch P (mm) . |
Diamètre de rouleau d1 max (mm) Bamako, Mali. |
Kɔnɔna tabali ni ɲɔgɔn cɛ bonya b1 min (mm) . |
Diamètre de broche d2 max (mm) Bamako, Mali. |
Pin janya L max (mm) . |
Pin janya Lc max (mm) . |
Kɔnɔna plati juguman h2 max (mm) . |
Plaque ka bonya T max (mm) . |
Tensile fanga min (kN/lbf) . |
A ka girinya hakɛ dantɛmɛnen Qo (kN) . |
A girinya mɛtɛrɛ kelen q (kg/m) . |
|---|---|---|---|---|---|---|---|---|---|---|---|
*20AF44 ye |
31.750 |
19.05 |
32.00 |
9.53 |
53.5 |
57.8 |
30.00 |
4.00 |
86,7/19490 sàn |
99.70 |
4.820 |
*24AF27 ye |
38.100 |
22.23 |
75.92 |
11.10 |
101.0 |
105.0 |
35.70 |
4.80 |
124,6/28010 kɔnɔ |
143.20 |
9.810 |
*06BF27 ye |
9.525 |
6.35 |
18.80 |
3.28 |
26.5 |
28.2 |
8.20 |
1.30 |
9,0/2045 kɔnɔ |
9.63 |
0.770 |
*06BF31 ye |
9.525 |
6.35 |
16.40 |
3.28 |
23.4 |
24.4 |
8.20 |
1.30 |
9,0/2045 kɔnɔ |
9.63 |
0.660 |
*06BF71 ye |
9.525 |
6.35 |
16.50 |
3.28 |
24.5 |
25.6 |
8.20 |
1.30 |
9,0/2023 sàn |
9.63 |
0.830 |
08BF97 ye |
12.700 |
8.51 |
15.50 |
4.45 |
24.8 |
26.2 |
11.80 |
1.60 |
18,0/4989.6. Bamako, Mali |
19.20 |
0.980 |
*08BF129 ye |
12.700 |
8.51 |
35.80 |
4.45 |
45.1 |
46.1 |
11.80 |
1.60 |
18,0/4989.6. Bamako, Mali |
19.02 |
1.500 |
10BF21 ye |
15.875 |
10.16 |
42.83 |
5.08 |
52.7 |
54.1 |
14.70 |
1.70 |
22,0/5000 ye |
25.30 |
2.260 |
10BF43 ye |
15.875 |
7.03 |
27.80 |
5.08 |
39.0 |
40.6 |
14.70 |
2.03 |
22,4/5090 kɔnɔ |
25.76 |
1.140 |
*10BF43-S ye baara kɛ |
15.875 |
10.00 |
27.80 |
5.08 |
39.0 |
40.6 |
14.70 |
2.03 |
22,4/5090 kɔnɔ |
25.76 |
1.800 |
*16BF75 ye |
25.400 |
15.88 |
27.50 |
8.28 |
47.4 |
50.5 |
21.00 |
4.15/3.10 kɔnɔ |
60,0/13488 ye |
66.00 |
3.420 |
*16BF87 ye |
25.400 |
15.88 |
35.00 |
8.28 |
54.1 |
55.6 |
21.00 |
4.15/3.10 kɔnɔ |
60,0/13488 ye |
66.00 |
3.840 |
*16BF114 ye |
25.400 |
15.88 |
49.90 |
8.28 |
69.0 |
72.0 |
21.00 |
4.15/3.10 kɔnɔ |
60,0/13488 ye |
66.00 |
4.740 |
*20BF45 ye |
31.750 |
19.05 |
55.01 |
10.19 |
76.8 |
80.5 |
26.40 |
4,50/3,50 ye |
95,0/21356 ye |
104.50 |
6.350 |
*24BF33 ye |
38.100 |
25.40 |
73.16 |
14.63 |
101.7 |
106.2 |
33.20 |
6.00/4.80 ye |
160,0/35968 ye |
176.00 |
11.840 |
*Roller hakɛ bɛ bɔ baara kɛrɛnkɛrɛnnen na
KC duplex coupling chain bɛ coupling system dafalen dɔ dilan min bɛ se ka wuli ka bɔ ɲɔgɔn na ni sprocket fila ye. Pilon kelen bɛ don bolifɛn bolilan kan, tɔ kelen bɛ don bolifɛn bolilan kan. Fanga bɛ taa ni ɲɔgɔndan ye min bɛ to senna cakɛda wulilanw ni sprocket ɲinw cɛ. Duplex cakɛda jɔcogo bɛ sira Di danma-danma lamaga-lamagali ma sprocket fila ni ɲɔgɔn cɛ. O sɛgɛsɛgɛli min bɛ don a kɔnɔ, o bɛ sira di jɔyɔrɔko misɛnninw ma bolifɛnw ni bolifɛnw cɛ, k’a sɔrɔ a ma transmission datugu. Sani a ka jiribolo fla siri ɲɔgɔn na kosɛbɛ, a bɛ jiginni fanga Lasegin k’a sɔrɔ a bɛ sira Di fɛn dɔ ma min bɛ Yɛlɛma. O baarakɛcogo jɔnjɔn in b’a danfara Bɔ ɲɔgɔndan gɛlɛnw na ani fɛnw cicogo gɛlɛn caman wɛrɛw la.
Fɛn minnu nafa ka bon kosɛbɛ, i n’a fɔ kɔnɔna tabali, kɛnɛma tabali, pinɛw, bugunw ani wuluwuluw, olu bɛ dilan ni nɛgɛ ye min sugandira ka ɲɛ, n’o ye nɛgɛ ye min ka ɲi kosɛbɛ. O yɔrɔ kelen-kelen bɛɛ bɛ tɛmɛ ni taamasiyɛn tigitigiw ye, CNC masinw ani funteni furakɛli fɛɛrɛw fɛ minnu bɛ bɛn sariya ma walasa ka gɛlɛya, gɛlɛya ani sɛgɛn kunbɛnni balannen sɔrɔ. An bɛ sɛgɛsɛgɛli gɛlɛn kɛ donnafɛnw na fɛnɲɛnamafagalanw kulu kelen-kelen bɛɛ la. Taabolo kɔlɔsili bɛ kɛ sɛnɛko bɛɛ kɔnɔ, i n’a fɔ masinw muɲuni kɔlɔsili, funteni furakɛli paramɛtiri kɔlɔsili ani dugukolo sanfɛla labɛnni. O fɛɛrɛ ninnu bɛ gɛlɛyaw bali minnu tɛ bɛn ɲɔgɔn ma, fɛnw tiɲɛni ani sɛgɛn joona, o bɛ kɛ sababu ye ka masin baara sabatilen sabati walasa ka baara kɛ waati jan kɔnɔ.
K’a sababu kɛ fɛn ɲumanw ye ani funteni furakɛli kɔgɔlen ye, nin cakɛda duplex roller in bɛ fanga dɔgɔyalenba di a ma ani a bɛ se ka sɛgɛn kosɛbɛ. A bɛ se ka doni hakɛ dantigɛlenw sabati ani ka janya banbali kɛlɛ boli cyclique, shock doni ani daminɛ-dabila cogoyaw la tuma caman na. An ka fɛnsɛbɛnni caman bɛ tali kɛ fɛnw na minnu bɛ se ka kɛ fɛn ye min bɛ se ka kɛ fɛn ye min bɛ se ka kɛ fɛn ye min bɛ se ka kɛ fɛn ye min bɛ se ka kɛ fɛn ye min bɛ se ka kɛ fɛn ye min bɛ se ka kɛ fɛn ye min bɛ se ka kɛ fɛn ye. A kɛra dɛmɛnanw ye minnu ka girinya ka dɔgɔn wo, walima minnu ka girinya ka bon, i bɛ se ka modɛli ɲuman sugandi min bɛ bɛn i ka sistɛmu doni ma. A bɛ bɔli sabatilen mara ani ka dɔ bɔ tiɲɛni faratiw la minnu ma labɛn fɔlɔ baara kɛli kuntaalajan kɔnɔ.
KC ɲɔgɔndan cakɛdaw nafa belebele dɔ ye se ka kɛ ka jiribolo misali suguya saba minɛ minnu bɛ sɔrɔ ɲɔgɔn fɛ: paralɛli ɲɔgɔndɛmɛ, angular misalignment ani axial displacement fitinin. Cakɛda jɔcogo min bɛ se ka wuli, o bɛ doni barikamaw minɛ minnu bɛ sɔrɔ daminɛ waati, doni jiginni walima kɔrɔtɔko jɔli waati. A fana bɛ yɛrɛyɛrɛ dɔgɔya kosɛbɛ min bɛ tɛmɛ bolifɛn bolilan sira fɛ. O lakanani baara in bɛ dɔ bɔ sɛgɛn degun na birikiw, jirisunw sigilanw, hubuw ani jɛɲɔgɔnya tigitigi wɛrɛw kan. O de kosɔn, fɛnw tiɲɛni hakɛ bɛ dɔgɔya kosɛbɛ, wa, kunnafonidilan bɛɛ ka baarakɛ waati bɛɛ bɛ janya.
Duplex cakɛda bɛ sigicogo jɛlen dɔ ta. A sigili ni a falenni tɛ wajibiya ka prime mover ni driven minɛn minnu sirilen don ɲɔgɔn na, olu lamaga, k’u bila yɔrɔ wɛrɛ la walima k’u labɛn kokura. Baarakɛlaw ka kan ka ɲɔgɔndan yɔrɔ da wuli dɔrɔn walasa ka cakɛda bɔ walima k’a sigi joona. Ni i y’a suma ni gese couplings, diaphragme couplings ani disc couplings ye, a bɛ alignment calibration baara gɛlɛnw ban. Ladonni taabolo ka nɔgɔn ani u bɛ se ka faamuya. Ni fɛnw falen teliya la, o bɛ fɛn dilanni jɔli waati tigɛ kosɛbɛ, wa a bɛ ladonni baara kuntaalajan ni fɛnw musakaw dɔgɔya. Tumu kɛli tuma bɛɛ, o ye ladonni kɛcogo kɔrɔba ye.
Nin cakɛda in dabɔra teliya cɛmancɛ ni teliya dɔgɔman cikanw kama. A bɛ baara kɛ ni dannaya ye izini baarakɛcogo fanba la. A bɛ se ka boli ka taa a fɛ buguri bɛ yɔrɔ minnu na, baarakɛyɔrɔw la minnu ka ɲi ani yɔrɔ minnu funteni bɛ wuli ni danma ye. Cakɛda in bɛ se ka buguri muɲu koɲuman, nɛnɛfɛnw sɔgɔli, tulu nɔgɔlen nɔgɔli ani nɔgɔ misɛnninw. A bɛ kɛ kosɛbɛ izini sigidaw bɛɛ lajɛlen na, hali ni a man ɲi funteni camanba la, a bɛ kɛ ni fɛn ye min bɛ fɛn tiɲɛ kosɛbɛ walima ji jukɔrɔ ni furakɛli kɛrɛnkɛrɛnnen tɛ.
KC series duplex coupling chains bɛ tali kɛ kosɛbɛ izini fanga cicogo caman na seko ni dɔnko siratigɛ la. Masina minnu bɛ se ka kɛ cogoya la, olu ye ji pɔnpew ni tulu pɔnpew ye, ventilateur centrifuge, mixer ni agitateur, cɛsirilanw ni buruburuw, gear reducers ani speed units, pakew dilanni masinw, finiko masinw, sɛbɛnnikɛlanw ani sɛnɛkɛ masin suguya caman. O ye fɛn ye min bɛ se ka kɛ kosɛbɛ, min bɛ se ka wuli ka bɔ a nɔ na, ka ɲɛsin standard drive systems ma, yɔrɔ min na, a jɔcogo nɔgɔman, a ladonni nɔgɔya ani a ka sɔgɔsɔgɔ muɲuli bɛ bila jɔyɔrɔ fɔlɔ la.
Modeli minnu taamasiyɛn ye dolow (*) ye, olu ye cakɛda kɛrɛnkɛrɛnnenw ye minnu bɛ jɔcogo la, minnu kɔnɔna bonya bɛ kɛ ka kɛɲɛ ni mɔgɔw sago ye. O cakɛda kɛrɛnkɛrɛnnen ninnu ka rollo hakɛ tɛ sigi sen kan; a bɛ latigɛ ka kɛɲɛ ni kiliyan ka sigicogo yɛrɛ ye ani a ka baarakɛcogo wajibiyalenw. Sani komandi ka kɛ cogo la min bɛ kɛ cogo la, an bɛ se ka dimension jaw ni specification sheets ofisiyali di aw ka ɛntɛrinɛti jɛkulu ma walasa u k’a sɛgɛsɛgɛ ko a bɛnnen don. Paramɛtiri jɔnjɔnw bɛɛ i n’a fɔ bɔgɔdaga, wuluwulu cɛmancɛ, kɔnɔna bonya, pinɛ cɛmancɛ, pinɛ janya, plati janya, a sɔgɔli fanga ani a girinya mɛtɛrɛ kelen kɔnɔ, olu bɛ sɔrɔ ka segin u kan. Tumu ɲuman kɛli ka ɲi kosɛbɛ walasa ka sɔgɔsɔgɔninjɛ bɔnɛ dɔgɔya ani ka cakɛda baara waati janya.
Donghua de ye a dilan, KC coupling cakɛda bɛɛ bɛ tugu diɲɛ kɔnɔ roller cakɛda sariyaw kɔ. Sɛgɛsɛgɛli bɛ kɛ sɛnɛfɛnw dilanni kulu bɛɛ la cogo labɛnnen na, i n’a fɔ dimensions tolerance checking, destructive tensile strength testing, surface defects sɛgɛsɛgɛli ani assemblage verification. An bɛ stock labɛnnenba mara KC, AF ani BF seriyali jɔnjɔnw na walasa ka ci teliya la. An ka baarakɛlaw ka ɛntɛrinɛti jɛkulu bɛ dɛmɛ don fɛɛrɛko siratigɛ la yɔrɔ kelen na, i n’a fɔ modɛli sugandili bilasirali, paramɛtiriw bɛnkan ani ja lajɛ. Cakɛda furakɛcogo minnu bɛ kɛ ka kɛɲɛ ni mɔgɔw sago ye, olu bɛ se ka labɛn walasa ka sigiyɔrɔ kɛrɛnkɛrɛnnenw sɔrɔ ani baarakɛcogo kɛrɛnkɛrɛnnenw kama. An bɛ dɛmɛ fana di feereli kɔfɛ min bɛ jaabi di diɲɛ izini sannikɛlaw ma.